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ORIGINAL ARTICLE
Year : 2023 | Volume
: 37
| Issue : 1 | Page : 38-42
Low-vision intervention for oculocutaneous albinism in a Tertiary Eye Care Hospital in India
Sarika Gopalakrishnan1, Kalpa Negiloni2, R Vivek Suganthan2, Saranya Velu3, Rajiv Raman3
1 School of Chemical and Biotechnology, Shanmugha Arts, Science, Technology and Research Academy University, Thanjavur; Low Vision Care Clinic, Sankara Nethralaya, Chennai, Tamil Nadu, India
2 Medical Research Foundation, Sankara Nethralaya, Chennai, Tamil Nadu, India
3 Shri Bhagwan Mahavir Vitreoretinal Services, Sankara Nethralaya, Chennai, Tamil Nadu, India
Correspondence Address:
Rajiv Raman
Shri Bhagwan Mahavir Vitreoretinal Services, 18 College Road, Sankara Nethralaya, Chennai - 600 006, Tamil Nadu
India
Source of Support: None, Conflict of Interest: None
DOI: 10.4103/sjopt.sjopt_266_21
PURPOSE: The objective of this study on patients with albinism in different age groups was to compare their level of visual impairment with the low-vision intervention (LVI) and its benefit.
METHODS: The medical records of 72 patients with low vision secondary to albinism who were referred to the low vision care clinic from 2015 to 2017 were analyzed. This included the demographic profile such as age, gender, occupation, ocular history, visual acuity status, and type of low-vision device (LVD) preferred. The LVDs prescribed and its subsequent improvement was compared.
RESULTS: In this data, 70 (97.2%) people had oculocutaneous albinism and 2 (2.8%) had ocular albinism. Majority of the patients had hyperopic astigmatism 42 (58.3%) and with-the-rule astigmatism 58 (93.5%). Presenting mean visual acuity for distance was noted to be 0.88 logMAR which improved to 0.83 logMAR with the help of spectacle correction. The most commonly prescribed LVD was a dome magnifier for 15 (34.9%) patients. In all the patients, there was statistically significant improvement (P < 0.05) in near vision with the help of LVDs.
CONCLUSION: The study highlights the importance of appropriate LVI for each subdivided age group. Patients with albinism who have received medical and surgical treatment have no or a limited role in restoring useful vision.
Keywords: Albinism, low-vision devices, low-vision intervention, oculocutaneous albinism
The prevalence of albinism subtypes varies among different ethnic backgrounds, globally affecting approximately one in 20,000 individuals.[1] However, consistent with the reference,[2],[3] “OCA1: Prevalence is 1 in 40,000 worldwide but one among the foremost common forms in America and China (70% of cases); OCA3: Prevalence is 1:8500 of African individuals primarily in southern Africa. It also can be seen in Pakistani, German, Indian, and Japanese populations. The estimated worldwide prevalence of various types of oculocutaneous albinism (OCA) is approximately 1:30–40,000, at an average 1:17,000.[4] This suggests that around 1 out of 70 individuals carries a gene for OCA. Albinism is a group of heritable disorders with complete or partial melanin production.[4] One of the most common presentations is ocular albinism (eyes), or OCA, where the eyes, skin, and hair would be affected.[1],[5],[6] Foveal hypoplasia, nystagmus, strabismus, refractive errors, and photophobia are common clinical manifestations.[6] Moderate-to-high refractive errors such as myopia, hyperopia, and astigmatism are commonly noted in albinism.[7] Despite the refractive correction, the reduction in visual acuity persists due to foveal hypoplasia and nystagmus.[4],[8]
Visual acuity status in albinism varies from moderate-to-severe visual impairment.[1],[4] There is enough evidence that patients with albinism would have difficulty in visual activities such as viewing distant objects, reading fine print, and seeing computers. The presence of these visual problems may lead to the poor academic performance of children with albinism and will hinder an individual's overall development in his/her professional career. Therefore, it is important to study the need for appropriate low-vision intervention (LVI) to overcome these visual discomforts. Previous literature have dealt with visual deficits and refractive correction in people with albinism.[9] However, LVI studies in albinism cases are very limited.
It is important to understand the pattern of LVI provided and accepted by patients in the case of albinism. Consequently, the objective of this report was to evaluate the level of visual impairment and LVI provided to patients with albinism who presented to low vision care (LVC) clinic at a Tertiary Eye Care Center in India.
MethodsStudy population
The medical records of patients diagnosed with albinism who were referred to the LVC clinic for the first time between January 2015 and June 2017 at a tertiary eye care institute in India were recorded. Institutional review board approval was obtained to analyze the hospital-based data and the tenets of Helsinki were followed. All patients with the diagnosis of OCA and ocular albinism were included. General informed consent was obtained from every patient before the eye examination. The following information from the medical records was extracted.
Ophthalmic evaluation
The information regarding age, gender, and anterior and posterior segment evaluation were recorded.
Low vision care clinic evaluation
The following information was recorded.
History
Presenting visual symptoms, occupation, visual acuity in both the eyes, subjective and objective refraction, best-corrected visual acuity (BCVA), and associated ocular condition were noted.
Visual acuity
Distance and near BCVA using Bailey-Lovie logMAR visual acuity chart and MN read continuous English chart, respectively.
Subjective-objective refraction
Myopia and hyperopia were categorized as low, moderate, and high.
Low-vision device trial
A low vision trial was done by providing a single low vision device (LVD) or multiple devices to improve the visual acuity of patients with low vision. These devices include Dome Magnifiers (LVRC, HKSB) are magnifiers which are more comfortable for reading continuous text at convenient working distance.[10] Half-eye spectacle reading eyewear is reading glasses with high plus power and prism component so that it allows both eyes to read together comfortably. These are hands-free magnifier that gives a wider field of view and also helps in writing tasks.[10] Stand magnifiers (LVRC, HKSB) are the magnifiers that provide a wide range of magnifications but have constricted field of view comparatively. Pocket magnifiers (LVRC, HKSB) are magnifiers with a wide range of magnifications and are mostly used for spotting.[10]
The following formula was used to calculate the equivalent viewing power (EVP):
EVP = Presenting near visual acuity/Target visual acuity × 100/working distance (cm).[11] On the basis of the EVP formula, the required magnification was calculated and appropriate magnifiers were given to patients for trial based on their visual demands. Either a single or combination of optical and nonoptical devices was tried for patients based on visual acuity level, occupational or patient need and visual acuity improvement was documented. Patients were provided the instruction manual of the LVDs prescribed to use them independently and the need for adaptation with the device was explained to them. A detailed explanation of the use of the device and adaptation training with the preferred device was given to patients to enable them to handle the device independently.
Classification of age group according to their occupation
The management strategy for low vision patients varies with age and occupation since there are 2 prime factors that determine the need of the person. Hence, we have classified the age group into 3, i.e., school-going children (4–18 years of age), nonpresbyopic adults (19–40 years), and presbyopic adults (>40 years).
Statistical analysis included the descriptive statistic
Frequency, percentage, means, or medians according to the normal distribution and standard deviation (95% confidence interval) or interquartile range as appropriate, for the continuous variable Mann–Whitney U-test were performed. We processed and analyzed data using SPSS 20.0 (IBM Corporation, Armonk, NY, USA).
ResultsThe mean age of the participants was 17.9 years + 13.1 years, where more than half of the patients were below 18 years (n = 43, 59.7%). Out of 72 patients, 51 (71%) were men. A family history of albinism was reported in 24 (33%) patients. The educational and occupational status showed that 52 (72.2%) were students, 12 (16.7%) were employed, 3 (4.1%) were unemployed, one was (1.3%) homemaker and one (1.3%) was retired. Out of 72 cases, 38 (52.77%) patients were from rural and 34 (47.22%) from urban areas. Most commonly associated ocular features included nystagmus in 69 (95.8%) patients, foveal hypoplasia in 67 (93.1%), albinotic fundus in 65 (90.3%), transillumination defects in 51 (70.8%), strabismus in 25 (34.7%) and others, as shown in [Table 1].
Of 72 cases, 51 patients had previous glasses prescription and 12 of them reported difficulty for only distance (16.7%), 3 for only near (4.2%) and 56 for both distance and near (77.8%). These symptoms were noted since childhood (range 0–5 years) in 68 patients (94%). We noted that 51 patients reported (71%) complaint of photophobia, of which 8 (11.1%) of them were prescribed with tinted glasses elsewhere. Deutan color vision defect was found in 2 (2.77%) patients. Of the 72 cases evaluated, 31 (43.1%) had severe visual impairment, 30 (41.6%) had moderate visual impairment, 8 (11.1%) had mild visual impairment, and 3 (1.3%) had profound visual impairment or blindness.
Out of 72 patients, 42 (58.3%) had hyperopic astigmatism, 20 (27.7%) had myopic astigmatism, 4 (5.5%) had simple astigmatism, and 6 (8.3%) were noted to be emmetropes. With the rule, astigmatism was noted in 58 (93.5%) cases, against-the-rule astigmatism in two cases and oblique astigmatism in three patients. The degree of astigmatism ranged from 0.50 diopters to 6 diopters with a mean of 2.7 D ± 1.4D. High hyperopia was found in 13 (30.9%) patients and high myopia in 9 (45%) patients. The details of each refractive error are explained in [Table 2].[12]
Low-vision intervention
Most commonly preferred LVD for near-vision activities by school-going children was a dome magnifier (n = 15, 20.8%), followed by a portable video magnifier (n = 3, 4.2%). Bonita® mouse magnifier was preferred by one school-going child. A Dome magnifier was preferred by 9 (12.5%) and a portable video magnifier was preferred by 2 (2.8%) nonpresbyopic adults. Presbyopic adults 3 (4.2%) preferred half-eye spectacle for reading fine prints. Photophobia was treated by prescribing tinted spectacles 38 (52.7%) and in the form of clip-on filters over spectacles 12 (16.6%), as shown in [Table 3]. Majority of the patients preferred dark grey and dark brown color tints to alleviate photophobia.
The overall presenting mean visual acuity for distance was noted to be 0.88 logMAR and it improved to 0.83 logMAR with the help of spectacle correction. The mean near visual acuity for near had improved from N7.2 to N6.3 at 15 cm with the help of LVD. Spectacle correction was prescribed as single-vision glasses in 70.8%, bifocal glasses in 9.7%, and as separate near-vision glasses in 1.3% of the patients. Although there was no statistically significant improvement in the distance visual acuity, most of the subjects reported improved clarity of vision after LVI in the under 18 years and above 40 years category. There was a statistically significant improvement in prepresbyopic adults where the mean visual acuity improved from 0.84 logMAR to 0.79 logMAR (P < 0.05), as discussed in [Table 4].
Table 4: Visual acuity status before and after low vision care interventionNear visual acuity improvement was statistically significant in all three categories (P < 0.05) irrespective of the presenting visual acuity. This could be because of the recent advancement of assistive devices, which provides a wide range of magnification and various mode of contrast. The cost of the low-vision optical devices ranges from $10 to $15, for which most of the patients were affordable. However, a portable video magnifier costs around $150, which was also purchased by patients since it significantly improves the quality of vision.
DiscussionIn the current study, the grade of visual impairment, degree of refractive error, and preferred LVD in the case of albinism had been studied. This study highlights the improvement in visual function with the help of LVD in a specific population at a tertiary LVC clinic. Although previous literature have mentioned options of low vision correction and magnification of prescribed LVD in albinism,[9],[13],[14],[15] evaluation of visual improvement with LVD among different age groups of patients with albinism has not been reported earlier.
Majority of the subjects were male in our study, which was similar to previous studies.[9],[16] In this study, we obtained positive family history of albinism in 33%, which is comparable with Wolf et al.[17] (31%). Nystagmus is usually associated with OCA as per the previous literature,[1],[5],[18] which is congruent with this study, where 95.8% had nystagmus. Fonda's[9] study showed that the majority of the patients with albinism presented was below 20 years of age and Khanal et al.[16] reported that 44% of the patients were younger, which illustrates that medical intervention need to be provided as early as possible in their lives because it can limit a child's overall development. This is congruent with this study, where the below 18 years age group had maximum number of participants. The parents of the children group were educated on the need and importance of wearing spectacles constantly to improve their visual performance during their childhood. Moreover, Wolf et al.'s study showed excellent compliance for glass wear among the younger population.[17]
Literature reports that higher spherical and cylindrical refractive errors are associated with albinism, which is congruent with this study.[9],[19] Both hyperopia and myopia have been reported in this study which was also found in Khanal et al.[16] Although majority of the studies[1],[14] represent hyperopia to be common, few literature reported myopia to be more common refractive error.[17] Our study also reports hyperopia to be more common among people with albinism. However, the actual prevalence of refractive error in the albinism population would be investigated through cross-sectional studies. This study found that 4 participants (8 eyes) had refractive error >10D of myopia and 2 participants (4 eyes) had a refractive error of more than 10D hyperopia,[12] which was comparable to the study done by Pérez-Carpinell et al.[20] In agreement with previous studies which elicited larger amounts of cylindrical powers, especially with-the-rule (WTR), this study also shows strong associations of albinism with WTR astigmatism.[5],[16],[21] Albinism has significant associations with high refractive error, for which refractive intervention needs to be done early in life. In our study, the best refractive correction was prescribed in nearly 50% of the subjects below 18 years of age. Although LVD plays a major role in improving visual performance, appropriate refractive correction is always mandatory, which is supported by Fonda.[9]
Based on the EVP formula, the required magnification would be calculated and the type of magnifier shown for trial would be chosen based on the educational and occupational visual demands of the patients. It is known that accommodative response is reduced in low vision due to poor visual acuity, impaired contrast sensitivity, and a larger depth of focus.[22] Continuous reading at a closer distance in children with reduced accommodative and binocular functions could result in visual fatigue. When prescribing high-power lenses to children with low vision, it is important to evaluate and prescribe the appropriate correction considering the near visual acuity and working distance considering the effect of accommodative amplitudes.[23] Fonda's[9] study stated that an emmetropic child usually holds the reading material at a relatively closer distance using the accommodation. The LVD trial was carried out on patients whose visual acuity did not improve even after holding the reading material closer to their faces. The near LVD was prescribed for those who had difficulty in reading fine prints, even at closer distances to enhance their visual comfort. It also demonstrated that the final prescription depends on the size of the print to be read.[9]
Patients with albinism preferred dome magnifiers in the below 18 and 18–40 age groups, whereas spectacle model magnifier was preferred by those above 40 years of age group. Cut-away stand magnifier was preferred by patients below 40 years of age and none of them in the above 40 years group preferred this magnifier which could be due to postural difficulty. Patients above 18 years of age preferred pocket magnifiers, whereas those who were under 18 years of age did not prefer this magnifier. School-going students preferred a mouse model magnifier which can be connected to monitor for reading tasks. However portable video magnifier (Closed Circuit Tele Vision) was preferred in all three groups irrespective of age since the device has variable magnification levels and variable contrast modes for better viewing of fine prints. Faye[23] has emphasized the need for long-term training with the use of LVD, which gives better improvements. None of the patients preferred additional lighting or illuminated magnifiers during the trial. Tinted glasses were prescribed in the below 18 years of age group, whereas clip-on filters were preferred by people above 18 years of age to alleviate photophobia.
The strength of this study was the sample size of the subjects with albinism. This study highlights the importance of referral to an LVC clinic and intervention using appropriate LVD in terms of visual improvement, thereby enhancing an independent way of living. Ophthalmologists and Optometrists can play a significant role in the visual rehabilitation of patients with albinism to improve their quality of life. In the future, prospective studies can be conducted, including the visual symptoms, photophobia management, and associated systemic features such as reduced platelet count in OCA subtypes. Albinism causes amblyopia, low vision, and visual impairment, leading to educational and professional challenges, so optometrists need to provide optimal refractive correction and appropriate LVI, including filters for photophobia, as early as possible. Albinism consists of a spectrum of various deficits that require timely intervention from eye care professionals, which can be achieved by increased understanding and proper referral to LVC services.
ConclusionAge, disease stage, presenting complaints, complaints of photophobia, education, and occupation all influenced the selection of LVDs in Albinism patients. The majority of the patients in this study are school-age children who benefit from the LVD and have their daily life needs met to improve their academic careers with the help of a dome magnifier, with tinted glasses advised for half of the patients for outdoor activity. Adults and the elderly benefited equally from LVDs such as dome magnifiers and half-eye spectacles, which met their needs and improved their quality of life. All of these factors, however, appear to be interconnected. Understanding these factors can aid in tailoring low-vision rehabilitation to each patient. This can result in the proper dispensing of low-vision devices and, as a result, an improved quality of life.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
References
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