Abstracts
Allergy
Allergic eye disease studies indicate that:
1. An increased number and an abnormal distribution of eosinophils is present in conjunctival biopsies of patients with vernal keratoconjunctivitis (VKC).
2. Eosinophil and eosinophil products, such as ECP, are also increased in tears of VKC patients and, in hay fever conjunctivitis, accumulate during the late-phase of allergic reaction following specific allergen challenge.
3. Circulating eosinophils of VKC patients show a typical activation phenotypic profile which is associated with increased serum level of eosinophil cationic protein and eosinophil-derived neurotoxin/protein X.
Drugs modulating various aspects of eosinophil function (e.g., cetirizine ) could play a primary role in the treatment of allergic eye disease.
Bonini S et al., The eosinophil and the eye. Allergy, 1997, 52:34 Suppl, 44-7.
Antioxidants & eye disorders
Ocular Oxidants and Antioxidant Protection
Vitamin C, because of its high concentration in the eye, is thought to be a primary substrate in ocular protection. A significant age-related decrease in glutathione levels is believed to be a factor in the aged lens' greater susceptibility to oxidative stress and cataractogenesis. In animal vitreous humor, there are significant concentrations of cysteine, ascorbic acid, glutathione, uric acid and tyrosine. Hydrogen peroxide is a byproduct and a source of free radical reactions that is normally present in the aqueous humor of the eye.
Rose, Richard C., et al: Ocular Oxidants and Antioxidant Protection, Proceedings of the Society for Experimental Biology and Medicine, 1998:217:397-407.
Antioxidants (1)
To evaluate the relationships between dietary intake of carotenoids and vitamins A, C, and E and the risk of neovascular age-related macular degeneration (AMD), the leading cause of irreversible blindness among adults.
The multicenter Eye Disease Case-Control Study. (Five ophthalmology centers in the United States.)
A higher dietary intake of carotenoids was associated with a lower risk for AMD. Adjusting for other risk factors for AMD, we found that those in the highest quintile of carotenoid intake had a 43% lower risk for AMD compared with those in the lowest quintile.
Among the specific carotenoids, lutein and zeaxanthin, which are primarily obtained from dark green, leafy vegetables, were most strongly associated with a reduced risk for AMD (P for trend = .001).
A higher frequency of intake of spinach or collard greens was associated with a substantially lower risk for AMD
The intake of preformed vitamin A (retinol) was not appreciably related to AMD.
Neither vitamin E nor total vitamin C consumption was associated with a statistically significant reduced risk for AMD, although a possibly lower risk for AMD was suggested among those with higher intake of vitamin C, particularly from foods.
Increasing the consumption of foods rich in certain carotenoids, in particular dark green, leafy vegetables, may decrease the risk of developing advanced or exudative AMD, the most visually disabling form of macular degeneration among older people.
Seddon-JM et al: Dietary carotenoids, vitamins A, C, and E, and advanced age-related macular degeneration. Eye Disease Case-Control Study Group [see comments] [published erratum appears in JAMA 1995 Feb 22;273(8):622]. JAMA. 1994 Nov 9; 272(18): 1413-20.
Antioxidants (2)
Oxidative damage caused by free radicals has been implicated in the development of age-related macular degeneration (ARMD).
Then two over-the-counter (OTC) nutritional supplements that make claims about the antioxidant nutrients they contain (ICAPS-Plus and Ocuvite) were evaluated with respect to their ability to raise blood levels of two important antioxidant nutrients: zinc and beta-carotene.
Based on the diet survey, 26 of the 28 subjects were found to have deficient intakes; zinc and selenium were the most commonly deficient nutrients. Following a 2-week administration period, both ICAPS-Plus and Ocuvite significantly raised mean serum zinc levels 24.7 percent and 18 percent respectively; ICAPS-Plus significantly raised mean beta-carotene levels by 21.4 percent, but Ocuvite did not change the mean level significantly.
Based on the probable relationship between antioxidant levels and diseases such as ARMD, these results suggest that OTC supplements might be useful for selected patients.
Kaminski-MS et al: Evaluation of dietary antioxidant levels and supplementation with ICAPS-Plus and Ocuvite. J-Am-Optom-Assoc. 1993 Dec; 64(12): 862-70.
Antioxidants (3)
Reduced antioxidant defense of the retina secondary to poor nutrition and smoking combined with increased life expectancy and exposure to solar radiation can provide a triple assault on the aging retina. If left untreated, without prophylactic measures, 7.5 million American adults will suffer vision loss from ARM by the year 2020.
A conservative prevention/treatment strategy is presented involving identification of at-risk patients, solar radiation protection, nutritional counseling based on the new USDA Food Pyramid concept and vitamin/mineral supplementation if necessary for non-compliant high risk patients. Excessive vitamin intake of particular micronutrients has some drawbacks, and the optometrist should be aware of the implications of self-prescribed OTC ocular formulations, the difference between UV risk vs. "blue light hazard" and ongoing clinical trials.
Richer-SP: Is there a prevention and treatment strategy for macular degeneration? J-Am-Optom-Assoc. 1993 Dec; 64(12): 838-50.
Antioxidants (4)
Although numerous studies have been published about theprobable causes of age-related macular degeneration, arresting or preventing the disease continues to be an elusive goal.
The literature is reviewed to provide an overview of the relationship of the antioxidants to disorders such as heart disease,cancer, diabetes, arthritis, cataracts and macular degeneration.
Diseases associated with aging appear to have a common denominator: oxidative damage. Antioxidants have been extensively studied to determine if they can prevent or successfully treat these diseases.
Larger-than-recommended amounts of antioxidants need to be used earlier in life, for longer periods of time, to determine their effectiveness in arresting or preventing diseases of aging.
Cheraskin E: Antioxidants in health and disease. J Am Optom Assoc, 67(1):50-7 1996 Jan.
Eye color
Iris color can be affected by a variety of ocular disorders. It is suspected that iris color may not remain constant throughout life. These observations have drawn attention to the morphologic correlates of iris color and its regulation. Differences in the iris color of normal eyes are the result of variable amounts of melanin pigment granules within a constant number of melanocytes in the superficial stroma of the iris. These melanocytes seem to reach their genetically determined amount of melanin in early childhood, and their melanin content usually remains constant in adulthood.
Diseases such as Horner's syndrome and Fuchs' heterochromic iridocyclitis affect iris color, resulting in a decrease of iris pigmentation. Evidence suggests that melanin content of some melanocytes is subject to adrenergic regulation even past childhood.
Application of the prostaglandin analogue latanoprost, on the other hand, leads to an increase in iris pigmentation in some patients. Studies with cultured dermal and uveal melanocytes, as well as with uveal melanoma cells, however, show no increase in cell proliferation when treated with latanoprost in vitro.
The mechanisms by which latanoprost affects regulation of iris pigmentation requires further investigation.
Imesch PD et al., The color of the human eye: a review of morphologic correlates and of some conditions that affect iridial pigmentation. Surv Ophthalmol, 1997 Feb, 41 Suppl 2:, S117-23.
Conjunctiva
Conjunctival Impression Cytology (CIC)
One hundred seventy-eight children from three villages were studied in a cross-sectional fashion to evaluate the efficacy of conjunctival impression cytology (CIC) to characterize vitamin A status of individual children and populations of children and to examine the relationship of vitamin A status to nutritional status.
CIC was a poor indicator of an individual child's vitamin A status, it accurately characterized the risk of vitamin A deficiency of communities. Furthermore, vitamin A deficiency defined by circulating retinol measurements but not CIC is associated with poor linear growth.
Relationship between vitamin A deficiency, malnutrition, and conjunctival impression cytology. Fuchs-GJ; Ausayakhun-S; Ruckphaopunt-S; Tansuhaj-A; Suskind-RM. Am-J-Clin-Nutr. 1994 Aug; 60(2): 293-8.
Dietary fat & eye disorders
To describe the relationship between type and level of fat in the diet and the prevalence of age-related maculopathy.
Persons with intake of saturated fat and cholesterol in the highest compared with the lowest quintile had 80% and 60% increased odds for early age-related maculopathy, respectively, after adjusting for age and intake of beer. These relationships were not influenced by adjusting for several other potential confounding variables (carotenoid intake, intake of vitamins C or E in supplements, smoking, body mass index, time spent outdoors in the summer, gender, and history of diabetes, hypertension, or cardiovascular disease).
High intake of saturated fat and cholesterol is associated with increased risk for early age-related maculopathy in the Beaver Dam population. This supports the hypothesis that atherosclerosis or its risk factors are related to age-related maculopathy.
Mares-Perlman-JA et al: Dietary fat and age-related maculopathy. Arch-Ophthalmol. 1995 Jun; 113(6): 743-8.
Fatty acids & eye disorders
Determined the effect of alpha-linolenic acid (ALA) on the growth and visual function of term infants.
The fatty acid pattern of plasma phospholipids was determined shortly after birth and at approximately 21, 60, and 120 days of age.
Infants who received the formula with 3.2% ALA (LA/ALA ratio, 4.8) had higher plasma concentrations of phospholipid docosahexaenoic acid (DHA) but lower concentrations of arachidonic acid at 21, 60, and 120 days of age.
Mean weight of this group at 120 days of age was 760 gm less (p < 0.05) than the mean weight of the group that received the formula with 0.4% ALA (LA/ALA ratio, 44).
Despite differences in plasma phospholipid DHA contents among groups, neither VER latency nor amplitude differed significantly among formula groups or between any formula group and age-matched, breast-fed infants.
The highest versus the lowest ALA intake (or the lowest vs the highest LA/ALA ratio) resulted in higher plasma phospholipid DHA content from 21 to 120 days of age but was not associated with improved visual function as assessed by transient VER. Moreover, mean body weight of infants who received the highest versus lowest ALA intake was less at 120 days.
The lower LA/ALA ratios currently recommended for infant formulas should not be adopted until the effect of such ratios on growth are evaluated more completely.
Jensen CL et al., Effect of dietary linoleic/alpha-linolenic acid ratio on growth and visual function of term infants [see comments]. J Pediatr, 1997 Aug, 131:2, 200-9.
Free radicals & eye disorders
Age-related macular degeneration (ARMD) is a major cause of blindness in the elderly. Unfortunately, no proven form of treatment is currently available for the dry, atrophic form of ARMD seen in more than 90 percent of patients with this condition.
A recent theory suggests that ARMD is associated with damage to the retina caused by free radicals. If this is correct, it is possible that the damage could be prevented or moderated by supplementing the diet with specific antioxidant vitamins and minerals that enhance the body's natural defenses against free radicals.
van-der-Hagen-AM et al: Free radicals and antioxidant supplementation: a review of their roles in age-related macular degeneration. J-Am-Optom-Assoc. 1993 Dec; 64(12): 871-8.
Infection & eye disorders
All opportunistic infections of the eye have their origin in the suppression of the immune system of the host.
The immunosuppression can be acquired through the human immune deficiency virus or as a result of immunosuppressive therapy in solid-organ transplant recipients with a maintenance therapy of cyclosporin and prednisone or during chemotherapy in patients with myeloproliferative disorders.
Generally, in less than 2% could severe opportunistic infections of the eye, like cytomegalovirus (CMV) or herpes virus infection, be found in transplant and cancer patients with chemotherapy.
About 35-70% of patients with AIDS exhibit ocular manifestations of disease, so the most notable opportunistic infection with an incidence of 35% would be CMV retinitis. Less frequent are progressive outer retinal necrosis syndrome, Kaposi's sarcoma and optic neuropathies.
Recent advances in the diagnosis and special local therapies of the worst opportunistic infections in immunocompromised hosts are reviewed.
Guembel HO & Ohrloff C: Opportunistic infections of the eye in immunocompromised patients. Ophthalmologica, 1997, 211 Suppl 1:, 53-61.
Nutritional factors & eye disorders
Reviews the role of specific nutrients in cataract and macular degeneration formation. It is noted that these are major causes of blindness in the United States.
Nutrients that may have value in these conditions include zinc, taurine, vitamins A, B2, C and E, selenium, beta-carotene, N-acetylcysteine, ginkgo biloba and flavonoids. The authors have treated approximately 60 patients with macular degeneration utilizing intravenous zinc, selenium and other trace minerals.
"Nutritional Factors in Degenerative Eye Disorders: Cataract and Macular Degeneration", Gaby, Alan R., M.D and Wright, Jonathan V., MD, Journal of The Advancement of Medicine, Spring, 1993;6(1):27- 40.
Overview of eye disorders
A general overview of age-related macular degeneration, including its definition, classification, clinical findings and epidemiology.
Included are the differential diagnosis, histopathology, prevalence, risk factors, and natural history of each individual form. Also presented are the issues of optometric management, including clinical recognition of choroidal neovascularization, timely referral for retinal consultation and angiography, preventive therapies, current and emerging trends in the medical and surgical treatment, and appropriate follow-up.
Oshinskie-LJ: Age-related macular degeneration. Optometry-Clinics. 1996; 5(1): 25-53. (102 ref)
Retinol binding
Retinol-Binding Protein (RBP)
Blood samples (100-160 microliters) were obtained from 1360 children by a finger prick in heparinized collection tubes, and an LC-Partigen retinol-binding protein (RBP) kit was used for quantification of RBP in the plasma. Only three boys and two girls had plasma RBP that was equal to or more than 3.0 mg/dL (recommended cut-off for normal values).
None of the children included in this study had eye signs of vitamin A deficiency.
Plasma retinol-binding protein levels of children under five years of age in a displaced Sudanese community. el-Bushra-HE; Ash-LR; Neumann-CG. East-Afr-Med-J. 1994 Oct; 71(10): 647-50.
Socioeconomic factors
Although the impact of poverty on the health and development of children is readily acknowledged, the extent of accompanying visual functional and perceptual-motor disorders has not received very much attention. These visual disorders are shown to be linked with poverty.
Neurointegrative and concomitant visual problems can be the result of malnutrition, low birthweight, teenage pregnancy, and maternal complications of pregnancy are cited and discussed.
The role of the optometrist in diagnosing and treating children with visual and neurointegrative problems is reviewed. Special emphasis is placed on the potential for optometric intervention to improve the ability of disadvantaged children to respond more effectively to classroom learning and enable them to make fuller use of the intelligence they possess.
Solan HA & Mozlin R: Biosocial consequences of poverty: associated visual problems. Optom Vis Sci, 1997 Apr, 74:4, 185-9.
Video display terminals
Contents:
Video Display Terminals
Vision screening
Video Display Terminals (1)
Fatigue and dryness of the eyes can be a frequent complaint among individuals using video display terminals. This study evaluated a variety of factors effecting tear dynamics in 104 healthy office workers. Of whom, 45 were men between 20 and 69 years of age. Half of them used a computer on the average of 3 hours a day. Under relaxed conditions individuals blinked approximately 22 times per minute, while reading a book at table level 10 times per minute and while looking at the video display terminal seven times per minute. The palpebral fissure was 2.2 cm2 under relaxed conditions, 1.2 cm2 while the subjects were reading, and 2.3 cm2 while the subjects were working at the video display terminal. The rate of tear evaporation increased, as the area of exposed ocular surface increased. The increase was greater with larger surface areas.
This indicated the increase in evaporation was due not only to an increase in exposed ocular surface, but also to the qualitative instability of the tear film or very larger surface. This could be related to the thinning mucin and lipid layers. The authors concluded that the use of video display terminals are associated with reduced frequency of blinking and an increased rate of tear evaporation. Each of which can contribute to dry eyes. Artificial tears and special glasses may provide relief for dry eye symptoms. The width of the palpebral fissure can be reduced by placing the terminal at a lower height with the screen tilted upward.
"Dry Eyes and Video Display Terminals," Tsubota, Kazuo, MD and Nakamori, Katsu, Ph.D., New England Journal of Medicine, February 25, 1993;328(8):584.
Vision screening
Employees (# 571) were screened using computerized vision screening software (City Visual Systems Ltd). Risk assessments were completed for 293 display screen work-stations. Full eye examinations, carried out by optometrists, were performed on those who failed vision screening and on those who specifically requested an optometric assessment (# 112).
Results indicate that whereas the proportion of users experiencing visual and general symptoms differed markedly from department to department (28-82%), the median number of individuals failing the screening test was 25% (range 9-40%).
Those involved in uninterrupted display screen equipment work for prolonged periods reported visual and general work-related symptoms twice as frequently as those who spent less time working with DSE.
The outcome of full eye examinations confirmed that less than 5% of display screen users required spectacles solely for display screen use. Work-station analysis indicated that ergonomic problems were common.
The successful management of health risks from display screen equipment requires simultaneous attention to work-place design, working patterns and eye care.
Jackson AJ et al., Vision screening, eye examination and risk assessment of display screen users in a large regional teaching hospital. Ophthalmic Physiol Opt, 1997 May, 17:3, 187-95.
Vitamin A drops
Vit-A-Drops are now available for over-the-counter distribution as an unpreserved isotonic solution composed of polysorbate 80 and 5,000 I.U. of vitamin A packaged in a 15-ml bottle. It may be used as a rewetting agent for contact lenses, dry eyes, contact related disorders, hyperemia, conjunctivitis and neovascularization. Vit-A-Drops are applied three times daily for 30 days and prophylactively thereafter as needed.
"Vitamin A Lubricant Drops Available", Drug Therapy, February 1990; 102.
Psychotherapy
Eye Movement Desensitization and Reprocessing (EMDR) is a therapy roughly equal in efficacy to others currently available.
This treatment method is efficacious independent of the value of its component parts (e.g., eye movements) and is successful because it applies common and generally accepted principles of psychotherapy.
Ten curative principles of this procedure are discussed as reflective of sound psychotherapy practice.
Hyer L & Brandsma JM: EMDR minus eye movements equals good psychotherapy. J Trauma Stress, 1997 Jul, 10:3, 515-22.
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