BARBARA C. PICKAR, Employee/Cross-Appellant, v. COATES PLAZA HOTEL and MINNESOTA WORKERS= COMP. ASSIGNED RISK PLAN/BERKLEY RISK ADM=RS CO., INC., Employer-Insurer/Appellants, and FAIRVIEW HEALTH SERVS., MEDICARE/NORIDIAN, and BC/BS of MINN. and BLUE PLUS, Intervenors, and SPECIAL COMP. FUND.

 

WORKERS= COMPENSATION COURT OF APPEALS

MAY 8, 2008

 

No. WC07-220

 

HEADNOTES

 

CAUSATION - CONSEQUENTIAL INJURY.  Questions of medical causation are issues of fact for resolution by the compensation judge, and, where it was clear that the judge credited the employee=s history of the onset of her symptoms, and where the employee=s treating doctor was firm in his causation opinion, the compensation judge=s conclusion that the employee sustained an injury to her left eye that rendered her totally blind consequent to medical care and treatment provided to her for her work-related knee injury was not clearly erroneous and unsupported by substantial evidence, notwithstanding the absence of medical or other documentation of eye problems immediately following the work-related surgery.

 

PERMANENT PARTIAL DISABILITY - COMBINED RATINGS.  Where her Adisabled condition@ under the permanency schedules included her pre-existing right eye disability, and where her present condition, as brought about by her left eye consequential work injury, was complete loss of vision in both eyes, the employee was entitled to a permanency rating of 85% disability of the whole body, reduced by 24% by apportionment to account for her preexisting right eye injury.

 

Affirmed in part and modified in part.

 

Determined by: Pederson, J., Johnson, C. J., Rykken, J.

Compensation Judge: Gregory A. Bonovetz

 

Attorneys: Robert C. Falsani, Falsani, Peterson, Quinn, & Beyer, Duluth, MN, for the Respondent.  Douglas J. Brown, Brown & Carlson, Minneapolis, MN, for the Appellants.  John R. Baumgarth, Duluth, MN, for the Special Compensation Fund.

 

 

OPINION

 

WILLIAM R. PEDERSON, Judge

 

The employer and insurer appeal from the compensation judge=s finding of a causal relationship between the employee=s marked decrease in blood pressure following her work-related knee surgery and the onset of an anterior ischemic optic neuropathy in her left eye, and the employee cross-appeals from the judge=s award of compensation for a 24% permanent partial disability related to loss of vision in her left eye.  We affirm the judge=s finding on causation and we modify his award of permanent partial disability.

 

BACKGROUND

 

On September 22, 1991, Barbara Pickar [the employee] sustained an injury to her mid and upper back while working in the housekeeping department at Coates Plaza Hotel [the employer].  On that date, the employee was forty-three years old and was earning a weekly wage of $194.04, and the employer was insured by the Minnesota Workers= Compensation Assigned Risk Plan [the insurer], with claims administered by Berkley Risk Administrators Company, LLC.

 

In early 1996, the parties agreed to settle the employee=s claims arising out of her September 22, 1991, injury.  At the time of the settlement, the employee contended that, in addition to her mid and upper back, she had injured also her low back and right shoulder on September 22, 1991, and had sustained a consequential injury to her left knee while undergoing medical treatment related to her work injury.  The employer and insurer had denied liability for the alleged shoulder and knee injuries, but in a stipulation for settlement approved by a compensation judge on March 15, 1996, the parties agreed to settle all claims arising out of the September 22, 1991, injury, including claims based on the alleged consequential left knee injury.  Claims for Areasonable non-chiropractic medical expenses pursuant to Minn. Stat. ' 176.135@ were left open.  According to the stipulation, the employer and insurer agreed to Aprovide reimbursement for future medical expenses associated with the employee=s back and neck injuries and knee injury.@  The employer and insurer maintained their defenses with respect to the shoulder condition.

 

On April 9, 1997, the employee was seen by ophthalmologist Dr. Daniel Maryland, to whom she reported a one-week history of a dark film over her right eye.  She was reported at that time as being able to count fingers at a distance of one foot, and Dr. Maryland offered a diagnosis of optic neuritis.  The employee was subsequently followed by internal medicine specialist Dr. Michael Van Scoy, who administered high-dose steroids and ordered an MRI of the brain.  The MRI was read as completely unremarkable, and Dr. Mark Young, a neurologist, agreed that the employee=s history and examination were consistent with a diagnosis of optic neuritis.

 

On May 15, 1998, the employee was examined by ophthalmologist Dr. Stewart Hazel, who noted the employee=s history of vision loss in her right eye over the previous year.  The employee described her right eye visual acuity as Ashadowy@ and her central visual acuity as Ahazy.@  Dr. Hazel noted that the employee=s corrected visual acuity in the right eye was limited to counting fingers at three feet.  He found her to have 20/30 vision in the left eye, with reading vision Aabout the equivalent of 20/25.@  Dr. Hazel diagnosed optic atrophy of the right eye, concluding that the employee=s history and examination were Amost consistent with a vascular cause for this, probably an ischemic optic neuropathy.@  He referred the employee back to Dr. Van Scoy to review the possibility of an early ischemic event and recommended that she return for a complete exam in one year.  No claim has been asserted that the employee=s right eye condition is in any way related to her 1991 injury.

 

The employee continued to experience left knee problems following the 1996 settlement, and on September 1, 1999, she was seen by Dr. Van Scoy for a preoperative consultation at the request of Dr. Peter Goldschmidt of Northland Orthopedics.  Dr. Van Scoy noted that the employee was scheduled to undergo an arthroscopy with debridement of the patellofemoral joint, as well as an Elmslie tibial tubercle osteotomy procedure.  He noted also the employee=s history of optic neuropathy, with loss of vision in the right eye, and complaints of fatigue.  He noted that the history of fatigue was Alikely secondary to sleep apnea@ but that evaluation of that issue had been postponed.  Following his examination of the employee, Dr. Van Scoy cleared the employee for surgery, noting that A[s]he represents a low risk for anesthesia.@  Dr. Goldschmidt performed the surgery on September 8, 1999, and, according to his operative report, the employee tolerated the procedure well and was transferred to the recovery room in stable condition.

 

While in the recovery room following her knee surgery, the employee experienced a drop in her blood pressure from 150/75 to 80/40 and a decrease in her heart rate to twenty-seven beats per minute.  A doctor was notified, medication was administered intravenously, and the employee=s vital signs returned to normal prior to her being transferred to her hospital room.^[1]

 

The employee testified that her vision had been very adequate before her knee surgery.  She explained that her left eye compensated for her right eye blindness and that she was able to read by closing her right eye and focusing with her left.  She did acknowledge that, if she closed her left eye, she was unable to see much with her right eye and that, even with correction, she could not have read with her right eye alone.  The employee acknowledged that she relied on her left eye vision for the visual activities in her life.

 

The employee testified that in her hospital room later in the day following her surgery, she noted vision problems with her left eye when she tried to read.  She testified that, out of habit,

 

I opened a book and I thought something=s strange because the middle of the page was nothing there, so I figured maybe I=m just not awake, so I put it back down.  [My husband] says just to rest for awhile, so I did.  But then when I picked it up later, it=s the same thing.

 

The employee testified further that, although she was certain that her left eye symptoms came on right after surgery, she did not recall whether she personally reported them to a nurse or to her surgeon, Dr. Goldschmidt.  Daniel Pickar, the employee=s husband, testified that, when the employee told him that she couldn=t see to read, he found a nurse and brought her back to the room.  Mr. Pickar recalled that, when Dr. Goldschmidt stopped in to see the employee later that afternoon, Mr. Pickar and his wife told the doctor about her left eye symptoms.  Mr. Pickar recalled that Dr. Goldschmidt then looked at the employee=s eye and told her to rest and see what happened.  Also on the day of her surgery, the employee was visited by her son and daughter, Joseph Pickar and Christina Tracy.  Both recalled in testimony that the employee had stated that Joseph=s face looked fuzzy and that she had had trouble seeing it.  Ms. Tracy also testified that the employee had told her that she had tried to read but that there had been a blank spot in her vision.

 

The employee was discharged from the hospital on the day following surgery, September 9, 1999.  Mr. Pickar later testified that the employee told Dr. Goldschmidt at that time that her vision had improved and that she was able to focus.  He recalled also that he told the doctor then that he was very concerned about her visual symptoms in light of her right eye blindness.  Except for a reference to the employee=s right eye optic neuropathy, St. Luke=s Hospital medical records of the employee=s stay on September 8 and 9, 1999, contain no reference to any left eye symptoms or complaints to Dr. Goldschmidt or to the hospital staff.

 

One week later, on September 16, 1999, the employee was seen by Dr. Hazel for her yearly eye examination.  The employee testified that following her discharge from the hospital she continued to note an inability to see the central portion of whatever she was looking at.  The employee did not, however, tell Dr. Hazel of such symptoms, and his office notes do not reflect any history of the employee=s recent knee surgery or any complaints following that surgery.  On examination, Dr. Hazel noted that the employee=s right eye visual acuity was limited to an ability to count fingers at two feet.  Vision in her left eye remained 20/30, but, with prescription changes to her glasses, her overall vision was now 20/20.  Dr. Hazel=s examination revealed no changes in the employee=s left eye optic nerve since her 1998 exam, and Dr. Hazel recommended that the employee return for a complete exam in one year.

 

The employee was next seen on September 23, 1999, by Dr. Goldschmidt for a follow-up on her left knee.  On physical examination, the doctor recorded that her incision was healing nicely, and x-rays showed the osteotomy site to be well-positioned.  He recommended that she not put her full weight on the knee initially, increasing the weight bearing as tolerated over the next four weeks, and that she attend physical therapy in Hibbing.  With that he released her to return to sedentary work if such work was available.

 

On September 27, 1999, in a letter addressed to Mr. Tom Ehrbright^[2] responding to an inquiry regarding the employee=s disability status, Dr. Van Scoy reported that, A[a]t this point, although [the employee] does have a few medical issues, I believe that she would be adequately fit to pursue gainful employment.  At this time, I would not support a disability status.@^[3]

 

The employee was evidently seen for her initial therapy evaluation at Arrowhead Rehabilitation on September 29, 1999.^[4]  On October 1, 1999, therapist Carol Nachtmann noted that the employee had been able to perform exercises two to three times a day since they were prescribed at her initial visit.  The therapist noted an improvement in the employee=s ability to flex her knee, and the plan was to continue her therapy two times per week as directed by Dr. Goldschmidt.

 

The employee was first seen for complaints regarding her left eye on October 4, 1999.  On that date, the employee was unable to get in to see Dr. Hazel and was referred to Dr. Upali Aturaliya in Hermantown.  At that visit, the employee complained that she couldn=t see with both eyes.  She reported that two to three days after undergoing knee surgery the Avision went@ in her left eye.  Dr. Aturaliya, noting that the employee=s vision comes and goes, found her visual acuity with correction to be 20/200 in the right eye and 20/80 in the left eye.  On funduscopic exam, the doctor noted right optic atrophy and a swollen nervehead in the left eye.  After discussing the matter with Dr. Hazel and Dr. Van Scoy, Dr. Aturaliya referred the employee to ophthalmologist Dr. Jonathon Wirtschafter at the University of Minnesota.

 

The employee was admitted to Fairview University Medical Center under the care of Dr. Wirtschafter on October 4, 1999.  In the history provided on that date, the employee reported that, after knee surgery on September 8, 1999, Ashe experienced diffuse blurring of left eye vision which has worsened to today.@  She reported also that her visual acuity fluctuates.  According to a later discharge summary, Dr. Wirtschafter noted that the employee=s visual acuities were 20/200 in the right eye and 20/100 in the left eye.  Upon examination, he found significant Aa small cup with chalky, white pallor disk in the right eye and mild elevation in blurred disk margin in the left eye.@

 

While the employee was hospitalized at Fairview University, the employee=s mother contacted Arrowhead Rehabilitation on behalf of the employee.  On October 6, 1999, the therapist=s progress note reported,

 

We received a call today from [the employee=s] mother who informed us that [the employee] had problems this weekend and was admitted to the hospital in Minneapolis.  She is still there and there is no date of release set yet.  Apparently, she lost sight in both of her eyes and her mother stated they will call to resume PT when [the employee] returns home.  Client is therefore placed on hold from PT at this time until further notice.

 

On October 9, 1999, the employee underwent bilateral temporal artery biopsies to rule out giant cell arteritis, performed by Dr. Wirtschafter.  In his operative report, Dr. Wirtschafter explained,

 

The patient is a 51-year old woman who had acute episode a year ago of loss of vision in the right eye.  She was left with 20/200 acuity and marked optic atrophy.  Workup at that time showed no evidence of multiple sclerosis, vasculitis, or giant cell arteritis, as judged by sedimentation rate. . .  She was referred on October 6, 1999 [sic] for an acute event in the left eye, which appeared to be quite similar to the event in the right.  Her vision was at the 20/100 level.  Because it was unclear whether this was demyelinating arterial in the sense of nonarteritic anterior ischemic optic neuropathy or arteritic, the patient was placed on IV Solu-Medrol and subcutaneous heparin.  Visual acuity ceased to worsen and quality of vision may have improved in that eye.  Because . . . the differential diagnoses and the prognosis for the patient were so important, in addition to [an] MRI, a spinal tap was performed to help settle the issue of whether this could possibly be giant cell arteritis.

 

No evidence of temporal arteritis was found, and Dr. Wirtschafter diagnosed ischemic optic neuropathy of the left eye.

 

On October 15, 1999, the employee was seen in follow-up by her internist, Dr. Van Scoy.  The employee mentioned to the doctor that her right eye vision had become poor after anesthesia for an earlier surgery.  The doctor noted then that, A[l]ikewise, she had just recovered from shoulder [sic] surgery recently, when her left eye vision became poor.  This occurred just three days after a visit with Dr. Hazel.  Unclear whether there is a relationship between general anesthesia and loss of vision.@  Dr. Van Scoy went on to state, AJust a month ago, prior to her vision loss, I had approved a light workability status for her,@ but Acurrently, she is unable to distinguish shapes and so is unable to work.@  In discussing possible etiologies with the employee, Dr. Van Scoy indicated that he was at a loss to explain these events of vision loss.

 

The employee was seen in follow-up by Dr. Goldschmidt on October 25, 1999.  The employee reported significant improvement in her knee since surgery but that A[u]nfortunately she has had some recent visual problems and has been referred to the U of M where she underwent bilateral temporal artery biopsies.@

 

The employee was eventually diagnosed with bilateral anterior ischemic optic neuropathy [AION], and she continued to be seen for periodic evaluations.  Ultimately, in a letter addressed to the employee=s counsel on April 22, 2005, Dr. Hazel related the employee=s left eye condition to her episode of decreased blood pressure in the recovery room following knee surgery on September 8, 1999.  Dr. Hazel explained that

 

[s]ome experts feel hypotension plays a significant role in the pathogenesis of nonarteritic anterior ischemic optic neuropathy.  Individuals are felt to be predisposed to this because of a smaller than normal optic nerve.  This smaller than normal optic nerve results in crowding of the nerve tissue and blood vessels.  This results in an increased resistance to blood flow in the blood vessels supplying the nerve tissue at the anterior portion of the optic nerve.  This is normally not a problem when an individual has a normal blood pressure.  However, if the blood pressure drops below the normal range, the blood flow cannot overcome the resistance to flow from the crowding of the tissue at the anterior end of the nerve.  Thus an ischemic insult to the nerve occurs which causes further swelling which further reduces blood flow.

*          *          *

In reviewing my exam from prior to this episode, my description of her nerve is consistent with a nerve that is predisposed to this.  Also the fact that she had a prior episode involving her right eye would indicate that her nerve structure places her at increased risk.

 

On July 1, 2005, the employee filed a claim petition seeking payment of permanent total disability benefits continuing from September 8, 1999, as well as compensation for undetermined permanent partial disability, both related to a left eye injury that occurred while undergoing surgery for her compensable left knee condition.  In an answer to the claim petition filed July 19, 2005, the  employer and insurer denied a casual relationship between the employee=s left eye condition and the compensable medical treatment for her left knee. 

 

About a week later, on July 25, 2005, Dr. Hazel issued a letter rating the employee=s whole-body impairment under Minnesota Rules 5223.0030, the schedule in effect on the date of the employee=s 1991 work injury.  He rated the visual impairment in the employee=s right eye at 99.4% and that in her left eye at 91.8%.  He then calculated the percentage impairment to her visual system as a whole at 94% and then translated that to 85%, the maximum whole-body disability allowed for loss of vision under the rule.  The employee subsequently amended her claim petition to allege entitlement to compensation for an 85% permanent partial disability of the whole person.

 

Dr. Hazel testified by deposition on April 6, 2007.  It was his opinion that the employee=s episode of a drop in blood pressure at the time of her knee surgery was a substantial contributing factor in her loss of vision in the left eye.  Dr. Hazel described the cause and effect relationship as follows:

 

The mechanism is the - - the drop in blood pressure to a level where the oxygen supply to the tissue is inadequate and cell death occurs.  It can be small - - just a few or it can be a - - a global cell death, and - -and as a result of that, there are - - whenever cells die, there are inflammatory mediators released.  These inflammatory mediators then will cause swelling of the tissue.  As the tissue swells, it further collapses the blood vessels and further compromises the - - the loss of circulation and - - and increases the amount of cell death and swelling.

 

When asked how he accounted for the essentially normal left eye examination a week after the employee=s knee surgery, Dr. Hazel explained that the possible mechanism was that only a small area of the nerve was affected.  As that area of the nerve subsequently swelled, it affected the adjacent areas of the nerve and compromised the circulation in those areas.  They then swelled and basically continued in a snowballing process.  Dr. Hazel went on to state,

 

There may have been changes there on my exam that I might have missed because of one of the things we frequently do to determine if a - - if a nerve is normal, we compare side to side, you know, right eye to left eye.  Her right eye was already abnormal.  If her right eye had been normal, I might have picked up a subtle abnormality in the left eye.

 

The employee was examined at the request of the employer and insurer by ophthalmologist Dr. Alan Weingarden, on June 19, 2006.  Dr. Weingarden reviewed the employee=s medical records, obtained a history, performed an ophthalmologic examination, and issued a report on that same date.  The doctor also testified by deposition on May 4, 2007, after reviewing Dr. Hazel=s deposition testimony and the exhibits introduced at that deposition.^[5]  In Dr. Weingarden=s opinion, the employee=s left knee surgery was not a substantial or material contributing factor in the development of the employee=s left eye condition.  He found no evidence in the record that the employee=s ischemic optic neuropathy occurred immediately after her surgery, and he attributed her condition in part to sleep apnea, a known risk factor for AION.  He believed the employee=s history to be physiologically incompatible with her medical records.  Dr. Weingarden explained,

 

Ischemic optic neuropathy is an interruption of blood supply to the optic nerve.  It is seen with a swollen optic nerve, with loss of vision. [The employee] had her surgery on 9/8/99.  She was seen by Dr.Hazel on 9/16/99 which is eight days later.  There=s no mention of visual abnormality.  Her visual acuity is correctable to 20/20 which is our standard normal vision, and there=s no mention by Dr. Hazel that she has a swollen optic nerve.  It=s finally mentioned on an exam of 10/4/99 where her vision is now impaired at 20/80 and her - - she has disc edema which is the swelling of the optic nerve.  This is not compatible with her history that she gave in the immediate post or PAR area.^[6]  In addition, Dr. Van Scoy states on the 10/15/99 exam that [the employee] stated that approximately three days after seeing Dr. Hazel which would make it 9/19/99 she started having visual symptoms.  This, again, is inconsistent and not compatible, physiologically, with having a vision loss at the time in the PAR.

 

On the issue of permanent partial disability, Dr. Weingarden rated the employee=s left eye impairment at 24% of the whole person under Minnesota Rules 5223.0030.

 

The employee=s claim for benefits came on for hearing on May 22, 2007.  The two issues presented to the compensation judge were (1) whether the injury of September 22, 1991, was a substantial contributing cause of a consequential injury to the left eye and (2) whether the employee had sustained an 85% permanent partial disability based on the left eye injury.  At the outset of the hearing, counsel for the employer and insurer stipulated that the employee=s substantial loss of vision in the left eye, when combined with her lack of vision in the right eye, resulted in the employee=s being statutorily permanently totally disabled under Minnesota Statutes section 176.101, subdivision 5(a) (1) (1991).  In a findings and order issued August 2, 2007, the compensation judge determined that the employee suffered a complete loss of vision in her left eye as a direct consequence of the medical care and treatment provided to her for her work-related left knee injury, and he awarded permanent total disability benefits continuing from September 8, 1999, compensation for a 24% permanent partial disability of the whole person, payment of related medical expenses, and costs and disbursements.  The employer and insurer appeal from the judge=s findings of causation of the employee=s left eye condition, and the employee cross-appeals from the judge=s determination as to the extent of permanent partial disability.

 

STANDARD OF REVIEW

 

In reviewing cases on appeal, the Workers= Compensation Court of Appeals must determine whether Athe findings of fact and order [are] clearly erroneous and unsupported by substantial evidence in view of the entire record as submitted.@  Minn. Stat. ' 176.421, subd. 1 (1992).  Substantial evidence supports the findings if, in the context of the entire record, Athey are supported by evidence that a reasonable mind might accept as adequate.@  Hengemuhle v. Long Prairie Jaycees, 358 N.W.2d 54, 59, 37 W.C.D. 235, 239 (Minn. 1984).  Where evidence conflicts or more than one inference may reasonably be drawn from the evidence, the findings are to be affirmed.  Id. at 60, 37 W.C.D. at 240. Similarly, A[f]actfindings are clearly erroneous only if the reviewing court on the entire evidence is left with a definite and firm conviction that a mistake has been committed.@  Northern States Power Co. v. Lyon Food Prods., Inc., 304 Minn. 196, 201, 229 N.W.2d 521, 524 (1975).  Findings of fact should not be disturbed, even though the reviewing court might disagree with them, Aunless they are clearly erroneous in the sense that they are manifestly contrary to the weight of the evidence or not reasonably supported by the evidence as a whole.@  Id.

 

A[A] decision which rests upon the application of a statute or rule to essentially undisputed facts generally involves a question of law which [the Workers= Compensation Court of Appeals] may consider de novo.@  Krovchuk v. Koch Oil Refinery, 48 W.C.D. 607, 608 (W.C.C.A. 1993).

 

DECISION

 

1.  Causation

 

In his findings and order, the compensation judge accepted the employee=s testimony that she had the onset of left eye symptoms Aupon rousing from the [e]ffects of the anesthesia@ administered during her knee surgery on September 8, 1999.  He then found that, when her vision continued to worsen, rather than rebound to its pre-surgery state as she had hoped, she sought medical attention on October 4, 1999.  The judge then adopted Dr. Hazel=s explanation that the employee=s marked decrease in blood pressure following her knee surgery had led to an ischemic insult to the optic nerve that in turn caused a cascading of events leading to the employee=s substantial loss of vision in the left eye.  In his memorandum, the judge indicated that he found Dr. Hazel=s opinion and his presentation of the basis for his opinion Amuch more convincing@ than Dr. Weingarden=s.

 

The employer and insurer contend that the judge=s finding that the employee=s left eye condition is a consequence of her September 8 ,1999, knee surgery is manifestly contrary to the weight of the evidence.  They argue that the judge=s findings fail to squarely address the key issue in the case - - the timing between the employee=s knee surgery and the development of her left eye condition.  The judge=s adoption of the employee=s version of events, they contend, was simply not reasonable in view of the entire record.  Specifically, the employer and insurer argue as follows: that the judge failed to issue any findings regarding the credibility of the various witnesses or to discuss credibility issues in his memorandum; that, given the employee=s history of pre-existing right eye visual impairment and the potentially devastating impact that might result from injury to the left eye, it is inconceivable that both the employee and her husband brought her left eye symptoms to the attention of the medical staff and physicians at St. Luke=s Medical Center, and yet no one there made a notation in the medical record of these complaints; that it was similarly unreasonable that, despite the employee=s allegedly being unable to see the central portion of whatever she was looking at, the employee should fail to provide any such history to her treating ophthalmologist at her September 16, 1999, exam; that, after examining the employee=s eyes on September 16, 1999, Dr. Hazel reconfirmed abnormal findings regarding the right optic nerve and a diagnosis of right eye neuropathy but specifically noted that the examination of the left eye optic nerve was normal, as were the employee=s left eye visual field and acuity; and that it was unreasonable that, despite alleged left eye symptoms superimposed on a pre-existing right eye optic neuropathy, the employee should make no mention of visual complaints to Dr. Goldschimdt on September 23, 1999, or to her physical therapist on September 29 and October 1, 1999.  We are not persuaded.

 

We agree with the employer and insurer that the compensability of the employee=s left eye condition is, in part, dependent upon the credibility of the employee=s version of events.  With regard to the employee=s credibility, and the credibility of the employee=s husband, son, and daughter, we will defer, as we most often do, to the unique perspective of the compensation judge.  See Brennan v. Joseph G. Brennan, M.D., 425 N.W.2d 837, 839-40, 41 W.C.D. 79, 82 (Minn. 1988) (assessment of a witness=s credibility is the unique function of the trier of fact), citing Spillman v. Mosey Fish Co., 270 N.W.2d 781, 31 W.C.D. 187 (Minn. 1978).  The judge was personally able to observe the employee=s testimony and the testimony of Daniel Pickar, Joseph Pickar, and Christina Tracy before coming to the conclusion that he did.  While the judge did not specifically comment on witness credibility, his acceptance of the employee=s testimony regarding events, and of her family=s characterization of her as a person reluctant to complain and more likely to focus on others, was implicit in his findings.  To the extent that there may have been inconsistencies in the witnesses= recollection of events, we note that the testimony was generally consistent in reference to the onset of the employee=s symptoms, and where it may have been inconsistent we find no critical bearing on the issue of causation.  Moreover, we note that all such testimony in this case referred to details and events that occurred almost eight years prior to trial.

 

It is the compensation judge=s responsibility as the trier of fact to resolve conflicts in expert testimony.  Nord v. City of Cook, 360 N.W.2d 337, 37 W.C.D. 364 (Minn. 1985).  In his memorandum, the judge found, as was his prerogative, that Dr. Hazel=s opinion and the basis for that opinion were more convincing than Dr. Weingarden=s.  Dr. Weingarden=s opinions emphasized his view that the employee=s medical records and her history of events were incompatible.  Dr. Hazel, on the other hand, was well aware of the fact that the employee=s eye complaints were not documented in the original hospital stay.  He was also aware that the employee=s left eye injury was not diagnosed at his examination on September 16, 1999.  Despite what would appear to be troubling inconsistencies, Dr. Hazel found the employee=s history of events to be consistent with the onset of ischemic optic neuropathy as a result of the marked drop in the employee=s blood pressure following her knee surgery.  In the end, as the employee has argued, a judge=s decision whether or not to rely on a given medical opinion that is being weighed in evidence is a matter of credibility, and a judge=s decision to do so is his prerogative.

 

The employer and insurer have not argued that Dr. Hazel lacked foundation to render an opinion; they simply contend that the judge should have instead chosen Dr. Weingarden=s opinion. They argue that the judge erred in his assessment of Dr. Weingarden=s opinion.  In his memorandum, the judge stated:

 

Aside from the fact that Dr. Hazel=s opinion and his presentation of the basis for his opinion are much more convincing, Dr. Weingarden, in arriving at his opinion, his determination [sic] may not have had essential facts or information.  Further, Dr. Weingarden fails to take into account much of the scholarly studies which Dr. Hazel has considered and which counsel for the employee has introduced into evidence.

 

The employer and insurer contend that, since the judge did not indicate how important these considerations may have been to his decision or how much he relied on his arguably erroneous determination that Dr. Weingarden was missing essential facts or information, the case must be remanded for reconsideration.  We do not agree.  While we acknowledge that the judge=s comments regarding Dr. Weingarden=s opinion are arguably at least vague and perhaps incorrect, we cannot conclude that the judge, in any material sense, has misconstrued the record.  It appears that, aside from any reservations that he may have had about Dr. Weingarden=s opinion, the judge still found Dr. Hazel=s opinion Amuch more convincing.@  Based on the entirety of the judge=s findings, order, and memorandum, we find no reasonable basis to remand the matter to the judge for reconsideration.

 

As we have often noted, it is not this court=s function to assess whether substantial evidence might support a factual conclusion contrary to that reached by the compensation judge; the court=s function on factual review is only to assess whether substantial evidence exists to support the conclusion actually reached by the judge.  Land v. Washington County Sheriff=s Dep=t, slip op. (W.C.C.A. Dec. 23, 2003).  In this case, we too are troubled by the absence of documentation of eye problems in the hospital records following the employee=s knee surgery, the employee=s normal left eye exam on September 16, 1999, and the lack of documented left eye complaints between the date of her knee surgery and October 4, 1999.  However, the compensation judge accepted the employee=s account of her history, and Dr. Hazel was firm in his causation opinion despite these facts, and such questions of medical causation are issues of fact which fall within the province of the compensation judge.  Felton v. Anton Chevrolet, 513 N.W.2d 457, 50 W.C.D. 181 (Minn. 1994).  In this case, we conclude that there is substantial evidence in the record to support the judge=s finding of causation, and we affirm.

 

2.  Permanent Partial Disability

 

Under Minnesota Rules 5223.0030, subpart 1, permanent partial disability for complete loss of vision in both eyes is rated at 85% of the whole body.  Under that same subpart, disability for complete loss of vision in one eye is rated at 24% of the whole body.  In the present case, the compensation judge determined that the employee is entitled to compensation for a 24% permanent partial disability under the rule, explaining in his memorandum that, Asince the employee lost vision in only one eye as a consequence of the work injury the employee is entitled to permanent partial disability based on the loss of vision for that one eye.@  On cross-appeal, the employee argues that the employer is liable for permanent partial disability based on her complete loss of vision in both eyes and that the judge erred as a matter of law in his application of the permanent partial disability rules.  She argues that, because she was already blind in one eye before her consequential injury, her consequential injury caused her to become totally blind.  The only question remaining, she argues, is whether the pre-existing permanency of the right eye should be apportioned.  We agree.

 

The employer and insurer argue that the judge correctly determined that the employee is entitled to benefits for only a 24% impairment under the rules and that his decision is consistent with this court=s holding in Bouchie v. Independent Sch. Dist. No. 633, 42 W.C.D. 712 (Minn. 1989).  In Bouchie, the employee, a lifelong diabetic, suffered a work-related injury to his left eye in 1984.  After the 1984 injury, the employee=s sight in the injured eye deteriorated, resulting in blindness.  A doctor opined that the work-related injury aggravated the pre-existing diabetes to cause blindness.  The employer and insurer accepted liability, paying 24% permanent partial disability under the rules.  The employee then went blind in the right eye as a result of the diabetes.  This blindness in the second eye was not work-related.  A panel of this court held that there was no factual, medical, or legal basis to support the employee=s claim for total blindness.

 

We agree with the employee that Bouchie is distinguishable from the present case.  Here, the employee=s total blindness is linked to the work injury.  She was already blind in one eye when she sustained the work-related injury that rendered her totally blind.  Mr. Bouchie, on the other hand, was rendered totally blind as a result of a development in his diabetic condition, unrelated to his work.

 

Permanent partial disability under the eye schedule is calculated by determining the employee=s impairment of the visual system.  While each eye may be measured under the eye schedule=s coordinated factors for vision, ratings for each eye are ultimately combined to arrive at impairment of the total visual system and then translated to a percentage of disability of the whole body.  Therefore, with respect to a complete loss of vision in one eye, the 24% rating applies only if vision in the other eye is completely normal.  To hold otherwise would inappropriately limit an 85% rating only to individuals who sustain an injury to both eyes simultaneously.  The permanent partial disability schedules contain no such requirement.

 

It is undisputed in this case that the employee suffered a complete loss of vision in her right eye prior to her consequential left eye injury.  Her right eye vision loss was caused by anterior ischemic optic neuropathy, the same disease that caused her left eye vision loss.  Because the employee=s Adisabled condition@ under the permanent partial disability rules necessarily includes a right eye condition that was not injured or made worse by the work injury, we believe it would be unjust to burden the employer with that portion of the employee=s disability which is not work-related.  While this case does not fit neatly under the provisions of Minnesota Statutes section 176.101, subdivision 4a, we believe that application of apportionment in this case permits fair relief to the employer and insurer without diminishing the employee=s entitlement to fair compensation for her injury.

 

In this case, the employee=s Adisabled condition@ under the permanent partial disability schedules includes her pre-existing disability.  The employee=s present condition, as brought about by her work injury, is complete loss of vision in both eyes, and she is entitled to a permanency rating of 85% disability of the whole body.  Based on medical records prior to her consequential injury, the employee had, at a minimum, a 24% impairment of the whole body attributable to her loss of vision in her right eye.  We therefore modify the judge=s award of permanent partial disability benefits to reflect compensation for a 61% whole body rating, to more accurately reflect the employee=s impairment following her work-related left eye injury.