“Clinical Findings and the Low Vision Evaluation and Rehabilitation of Age-Related Macular Degeneration”, American Academy of Optometry: Case Report 2

 
Abstract

Age-related macular degeneration is the leading cause of severe vision loss among the elderly in the United States.  In this condition, central vision is lost, but peripheral vision is generally spared and almost always remains intact.  The diagnosis of age related macular degeneration is based on symptoms and ophthalmoscopic findings, and the disease can be classified into two main types, dry (atrophic) and wet (exudative). 

There are several treatment modalities for wet macular degeneration, with new changes coming to the forefront with remarkable speed. Three to five years ago we saw a shift from thermal laser, which was the primary mode of treatment for wet macular degeneration, to photodynamic therapy, and in the last two years another shift to intra-ocular injections with drugs like Macugen, Lucentis, and Avastin. 

These have led to great changes in the ways that retinal surgeons are approaching the immediate and long term care of patients with the exudative forms of the disease. Low vision evaluation, treatment, and rehabilitation can help patients maximize their remaining vision and gain the most function to assist them in adaptation and performance of their activities of daily living. In addition they may be able to read, write, work, enjoy hobbies, and indulge in many activities that are visual in nature.  This case reviews the low vision evaluation such a patient and demonstrates various approaches that were used in her rehabilitation. 

Key words: Age related Macular Degeneration, Full diameter tele-microscope, geographic atrophy.

Introduction

Age related macular degeneration has been around for a long time, but its prevalence and demographics are rapidly changing as our population ages.  In the last 30 years we have seen a tremendous increase in the number of people affected with this condition. As the baby-boomers reach their golden years there will be another leap in the potential number of patients with this disease.   The pathophysiology of age-related macular degeneration is still under investigation.

The location of the disease also remains a subject of debate. Some investigators believe that the disease resides in the neural retina (rods and cones), while others are studying the retinal pigment epithelium, which provides nutrition to the neural layer.  There are several risk factors that seem to be universally agreed upon. The incidence of the disease goes up dramatically with smokers vs. non-smokers, this may be the single greatest risk factor, other then genetics.

Ethnicity demonstrates that the condition is much more common among non-Hispanic whites, especially those with fair skin and lightly pigmented irises.  Genetic predisposition is under investigation, but no definitive conclusions have been defined at this time. Exudative forms of the disease may be more common in women then men (1), and there seems to be only a weak association with cardiovascular disease (2). Diet and exercise also play a major role.

It has been demonstrated that diets that are high in fats and triglycerides tend to precipitate the condition while those high in green leafy vegetables and fruits, tend to stabilize or slow its progression. Excessive alcohol may also be a contributing factor to increasing the rate of progression.  Exercise of a cardio-vascular nature also seems to be of benefit in the oxygenation of the cells in the macula and retina.  

Patients with this disease will typically experience a blurring or distortion of their central vision.  This may ultimately progress to a total absence of central vision in the affected eye(s), as well as a loss or shift in color perception.  The diagnosis of the condition is made based on the subjective presence of the visual disturbances as well as the characteristic objective ophthalmoscopic findings. 

Classification of the macular degeneration into the exudative vs. atrophic types is further carried out using techniques such as fluroscein angiography. The atrophic form is generally monitored and the patient is instructed in those behaviors that will help to stabilize the disease and retard it’s progression.  These would include the risk factors mentioned previously.

In the wet form the retinal surgeon will evaluate the condition and determine the appropriate course of treatment which may range from observation to thermal laser, photodynamic therapy, or injections with steroids, macugen, lucentis, or avastin. Along with the vision changes there are often psychological changes that may include anger, and most often some level of depression, all of which need to be addressed.   Low vision services may also prove highly effective in evaluating the level of remaining vision and enabling the patient to take maximum advantage of their remaining sight.

Case Report

Patient #2 is kind and energetic woman of 80. She was first seen for evaluation for low vision services on July 30th,2001. She has been a bookkeeper for a title company for almost 30 years. In the last few years she is unable to see her computer monitor and her spread sheets so her employer has kept her on to answer the phone. 

She is very depressed by this as she feels that she isn’t earning her keep and that keeping her working is more or less a charitable gesture out of respect for the years of service and dedication she has provided to this employer.  She has been seeing the same retinal surgeon for the last 20 years. Her macular degeneration was initially atrophic, and remained as such for almost 11 years then it shifted to the exudative type, and she has received many laser treatments over the last nine-year period. 

With every examination and treatment she has asked the retinal surgeon if there is anything else that can be done to help her see and she has always been told that there is no additional help. She is very frustrated and depressed as a result of this. She changed surgeons and her new physician referred her for a low vision evaluation. She was  unable to read her mail, write on a straight line, or identify her medications.

She couldn’t see well enough to play cards, see her face in the mirror to put on her make-up, or see the dials on her oven. She could see the numbers on a large telephone well enough to dial, but couldn’t tell if a counter is clean or dirty without feeling it. She couldn’t read the signs on the front of buses so she was unable to use public transportation and of course she was no longer driving. 

She could identify the color of traffic lights, but not well enough to cross a street if she also had to judge the oncoming traffic. She could find curbs and steps if she was cautious, so she was able to ambulate safely. She couldn’t recognize peoples faces at a distance, and couldn’t make out the picture on the television. She didn’t go to the theater. Bright light and glare bothered her, but she wore filtered lenses which were of great assistance in this regard. Her most important goal was to see well enough to work on the computer and see her spread sheets so that she could return to the job she had been doing for 30 years.  

Her mother had a history of blindness at age 80, but she didn’t know what the cause was.  

Other than this her family health history was unremarkable.  Her personal health history included hypothyroidism, hypertension, type 2 diabetes (adult onset diagnosed at age 77) and high cholesterol.  She also had a history of breast cancer 30 years earlier. Her medications included lipitor, synthyroid, lopressor, glucophage, and acupril.  Her surgical history was limited to the breast cancer and binocular cataract extractions with posterior chamber implants in both eyes. 

She weighed 112 pounds, was 5’2” tall, and her blood pressure was controlled at 126/76.  Her unaided central distance acuity as reported by her ophthalmologist was OD counts fingers at 2’ and OS counts fingers at 4’.  She didn’t have any glasses as she said that they didn’t help her. Her pupils were normal round and reactive to light.

He motor fields were full in all directions of gaze.  Slit-lamp evaluation was clear and free of any observable pathology save arcus senilis OU. She had posterior chamber IOL’s OU with Yag Capsulotomies OU. Her anterior chambers were normal and the angles were clear and open.  She demonstrated a Von Herrick Ratio of 1:1 OU. Her Elschenig classifications were type-I OU and her A/V ratio was 2/3 OU. Depth of the cups at the disc were 2.00 diopters with a C/D ratio of .3 OU. With dilation and “Binocular Indirect Ophthalmoscopy (performed at the end of the examination), she demonstrated geographic atrophic changes OU with 2-3 disc diameters OD of atrophy directly on center and

approximately 3-4 disc diameters of atrophy OS displaced nasally with the temporal margin of the atrophy closer to center then the nasal edge.  There were no signs of NVD or NVE in either eye. No other signs of diabetic retinopathy were present. Her acuity measured with the Feinbloom/Designs for Vision Chart were OD 10/100 10 degree right fixation, and OS 10/80 5-10 degrees left fixation.  Her refraction was OD +.50-.75×075 and OS was plano-1.00×090, yielding no improvement in acuity. Her color perception OS was almost normal with only 3 reversals on the Farnsworth D-15. With a +4.00 add over the refraction she was able to read 3.2M type OD and 2.0M type OS. 

The differential diagnosis in this case centered around age related macular degeneration and diabetic retinopathy.  This patient had no signs of diabetic retinopathy and her diabetes was diagnosed only 3 years ago, at age 77. While she may have had the diabetes for several years before diagnosis, this conclusion would be unlikely as she had regular physicals and blood work, and was just above borderline blood sugar levels when the diagnosis was made and medication prescribed.  He visual history and the appearance of the macula/retina strongly supported the diagnosis of Age related macular degeneration.

Low Vision Evaluation

There were three main goals in the low vision evaluation.  First to establish the ability to read standard size type, 1.0M continuous print on her accounting spreadsheets.  Second to see well enough to write and follow a line, and third to be able to see continuous print on her computer screen of approximate size of 1.25M print.  To meet these goals the following considerations were made.  

1. Near point functions were going to be the most important.
2. The minimum level of magnification was to be used to permit the largest field of view with the greatest working distance.
3. The device had to be headborn leaving her hands free to work her keyboard and write.
4. The device needed to be portable, light, and comfortable to wear.
5. The device needed to be easy to use and adapt to.

Based on the above considerations a 1.7X Full Diameter Telemicroscope was the device initially chosen for this patient.  This device has a 26 degree field of view and with the introduction of the appropriate tele-microscopic caps the tasks as they relate to her goals could be met.  With the introduction of a 1.7X Full Diameter Telescope she was able to see 10/40 at distance (10) feet with an ocular of +1.00-1.00×090 placed in the trial frame.  With a +4.00 tele-microscopic cap she was able to read 1.0M continuous type at 10”, adequate for seeing her spread sheets. When a +2.50 diopter cap was used she could comfortably see her computer screen at 16 to 18”.  This device was ordered for her on the date of her initial low vision examination. When the device arrived 3 weeks later, she began her low vision therapy. This consisted of a series of exercises performed at near 

point working distance, in her case 10” with her +4.00 reading  cap. The therapy starts with targets for fixation and characters twice as large as her ultimate acuity as measured at the time of the examination.  In her case this was 2.0M print. It begins with single letters of this size and over 6 weeks the letters became gradually closer together and then made smaller.  The print was changed from single letter to short 2 , 3, and 4 letter words, and gradually to continuous print.

At the completion of her 6th session of therapy she was able to efficiently read 1.0M continuous print in the local newspaper, which has a fair level of contrast at best.  It was felt that a split tele-microscopic cap would be the best to service her needs at work and the field of view of the 1.7 scope lends itself to this application quite well.  

A cap with a top of +2.50 diopters and a bottom of +4.00 was created. This enabled her to look up and see her computer screen and look down and see her spread sheets. Upon dispensing of the cap 2 weeks later it seemed to do it’s job perfectly.  She was able to return to work as a bookkeeper and her level of frustration and depression was all but gone. In addition she was able to use the device with the split cap to read her mail, write, and even play cards.

Follow-UP #1

When she returned for her annual follow-up on March 3, 2002 she was still seeing as she had before.  There were no objective findings relating to progression of her disease and she was still going to work everyday. 

Follow-UP #2

In December of 2002 she called and explained that she had experienced a decrease in her vision and had a laser treatment as a result of some bleeding that had occurred in her left eye.  She returned to demonstrate a reduced acuity with the device resulting in distant acuity with the scope of 10/80 and a near point acuity of 2.0M continuous print with strain when using her split cap.  She once again was not able to function at work and was devastated.

We turned to the Florida Division of Blind Services for assistance and were able to get them to give her a CCTV and a Zoom Text program.  With the CCTV should could magnify the print on her spreadsheets to the point that she could easily see them with tele-microscope with the cap, and with the Zoom Text at the 2x setting could see the computer well enough to do what she needed to.  She liked this combination as it put much more information on the screens of the CCTV and the Computer then she would have by using these devices at higher levels of magnification. She had become so comfortable with the device that using it in this manner made much more sense to her.

Follow-UP #3

December 2, 2004 she returned for a bi-annual evaluation.  She had worked for almost an additional year with the combination of instruments, then her family moved, so she missed her annual exam.   She returned for a visit and decided to spend some time with us. She could still see well enough to work, but was presently not working in her new location and had decided to retire.   There has been no word since that last exam, but it was truly an honor and pleasure to work with such an energetic and directed woman.

Discussion

Age-related macular degeneration is the leading cause of severe vision loss in older Americans. (3).  Elderly persons are concerned about losing independence and mobility. Studies have shown that loss of central visual acuity leads to a reduction of daily activities and mobility in the elderly.  (4) Loss of central visual acuity also increases the risks of falls, fractures, and depression in this population(9). With a loss of central vision there is a decrease in function to the point where the patient may have increased difficulty to total loss of functions in activities like reading, writing, seeing the food on their plates, their faces in the mirror, and a myriad of other things.  

Age-related macular degeneration has been examined in many population-based epidemiologic studies. (5)  The estimated prevalence of the disease was 9.2 percent among civilian, non-institutionalized persons 40 years of age and older.  Macular degeneration was noted to be more prevalent in non-Hispanic whites then in blacks or Mexican Americans.

The survey also included other Hispanic groups, as well as Asian Americans and Native Americans, but their numbers were too small for meaningful comparisons.  Early age-related macular degeneration was found to be more prevalent in persons 60 years of age or older then in persons 40 to 59 years of age. Late disease was only found in persons 60 years of age and older. (6) Few studies have evaluated the incidence of age-related macular degeneration.

In the Beaver Dam Eye Study, (7) pure geographic atrophy was 16.6 times more likely to develop in persons 75 years of age then in persons who were younger at baseline.  The incidence of exudative changes increased from zero percent in persons less than 55 years of age to 1.8 percent in persons 75 years or older at baseline. In early disease, the macula shows yellowish-colored sub-retinal deposits called drusen and/or increased pigment.

Drusen are thought to be byproducts of retinal pigment epithelium dysfunction. In most eyes with early disease, visual acuity may remain stable for many years, and loss of vision is usually gradual.  Late disease, exudative or atrophic, can lead to significant loss of vision. Exudative disease occurs in only about 10 % of patients with Age-related macular degeneration, but it is responsible for 80-90% of cases of severe vision loss related to the disease. (8) In the atrophic stages, the macula usually shows areas of de-pigmentation. In the exudative form, fluid can accumulate underneath the retina, as pigment epithelial detachments or sub-retinal neovascularization, and loss of vision is usually rapid.

Fluroscein angiography can be used to confirm the diagnosis and to help determine whether a patient has the atrophic or exudative form of the disease. In most instances, this modality is employed to determine whether and eye with exudative disease is eligible for some form of therapy. These may include laser, photo-dynamic therapy, or injections such as Avastin or Luecentis.  

In any case it is critical to explain the condition to the patient.  The patient has a much better chance for any level of success if they have a clear understanding of what they are dealing with.  They should know the treatments available to them, the extent of their disease, and have a good understanding of what things they may do to stabilize their condition and take maximum advantage of their remaining vision. 

To stabilize their conditions they may want to consider the following.  First if they smoke they should be encouraged to stop immediately. If they have children who smoke they should be cautioned about this as well.  Patients in their 40’s or older who show signs of drusen should be made aware of all of these options as well. In addition to the cessation of smoking they should be encouraged to decrease alcohol consumption to no more than 1 ounce per day.  If their diets are high in fats and triglycerides decreasing this intake will prove beneficial as well. They should be encouraged to have diets that are high intake of fruits and green leafy vegetables. They should exercise regularly, and the exercises should be cardio-vascular in nature.  In addition to these they should always protect their eyes from excessive exposure to ultra-violet radiation, so sunglasses, coatings, and filters that protect in this manner should always be worn when exposed to this light spectrum. If their diets aren’t comprehensive in these areas then supplements that will make up these deficits should be prescribed.  

Once stabilization is considered then the next thing is to determine the residual visual function that is still present.  Any ways and means available should be exercised to have these patients derive maximum benefit from their remaining sight.  A comprehensive case history will reveal the levels of activities that the patient can and can not participate in. Once established, a list of the goals and visual aspirations of the patients need to be obtained. This list needs to be reviewed to narrow it down to things that may be attainable and realistic. 

The remaining vision needs to be evaluated. This should be done by finding those areas in each eye that sill possess some level of vision. These areas need to be measured as to their relative size and sensitivity. Once this has been accomplished then an accurate refraction needs to be performed using the most logical area of remaining tissue.  Based on this and the remaining goals a device should be designed or selected that permits the patient to see at this level.

A program of rehabilitative therapy must now be created that will teach the patient to use the area of tissue to its maximum advantage along with the device or devices to be utilized to meet the visual goals. The considerations in the selection of the devices should utilize the least expense, and the simplest instrument that will permit the patient to meet their goals. 

It is always possible to go to a more expensive and complicated device, but generally the simpler less expensive devices tend to have the greatest latitude in function and use. The device should work at the least level of magnification that will meet the patients needs as this will generally result in the widest field of view and the longest working range, giving the patient the most natural working condition.

Conclusion

This case study demonstrates the importance of a low vision examination, treatment, and rehabilitation.  It follows a patient from what was a very frustrating and depressed existence to one of hope, function, independence, enhanced self-esteem and worth.  It further shows that as the disease progresses that the treatment and rehabilitative efforts can be enhanced to frequently meet the changing needs of the patient. 

It is important to let the patients know what they can do pro-actively to stabilize their conditions, and to disseminate the information they have to family, especially children and grand-children, and to friends who may be similarly challenged.  It is critical to encourage and enlighten those treating patients with Age-related macular degeneration that there is a lot of life that can still be had with the proper care and motivation, and that there is a genuine need for a continuum of care for these patients.

Bibliography

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