Pattern visual evoked potential and foveal sensitivity in amblyopia.

PURPOSE: Amblyopic eyes show impaired visual functions such as poor visual acuity and reduced foveal sensitivity. The purpose of this study was to determine the association between foveal threshold and visual evoked potentials (VEP) in strabismic and anisometropic amblyopia. METHODS: Forty-five subjects (age range: 7-28 years, 43.3% female) including 15 strabismic and 15 anisometropic amblyopes, and 15 age-similar control subjects participated in this study. Each subject had pattern visual evoked potentials and foveal threshold recorded in each eye using RetiScan (Roland Consult, Germany) and Humphrey Visual Field Analyzer II (HFA II; Carl Zeiss Meditec Inc., Dublin, CA), respectively. These outcomes were compared among the amblyopic eyes, their fellow eyes, and the control eyes. RESULTS: Compared to the amblyopic eyes (Mean ± SD: 33.4 ± 3.48 dB), the foveal threshold was higher in fellow eyes (37.0 ± 2.04 dB, p = 0.0002) and in control eyes (38.7 ± 0.96 dB, p < 0.0001). Strabismic amblyopes had a lower foveal threshold than anisometropic amblyopes (31.8 ± 3.86 vs. 35.0 ± 2.17 dB, p = 0.005). Relative to the P100 peak time in fellow eyes (1° checks:116.1 ± 9.00 ms; 0.25° checks:118.8 ± 5.67 ms), amblyopic eyes had delayed P100 peak times for both 1° (122.7 ± 11.4 ms, p < 0.0001) and 0.25° (130.4 ± 11.2 ms, p < 0.0001) check sizes. There were also significant differences in P100 peak time between amblyopic and control eyes (1°:122.7 ± 11.4 vs.112.4 ± 5.01 ms, p = 0.15; 0.25°:130.4 ± 11.2 vs.113.9 ± 5.71 ms, p < 0.0001) and between fellow and control eyes (0.25°:118.8 ± 5.67 vs.113.9 ± 5.71 ms, p = 0.009). Amblyopic eyes exhibited lower N75-P100 amplitudes than fellow eyes (1°:12.6 ± 7.96 vs.15.9 ± 8.82 µV, p = 0.01; 0.25°:10.6 ± 6.11 vs. 15.8 ± 10.6 µV, p = 0.001) and control eyes (0.25°: p = 0.0008). Foveal threshold correlated negatively with P100 peak time (1°: r = -0.45, p = 0.002 and 0.25°: r = -0.58, p < 0.0001) and positively with N75-P100 amplitude responses (1°: r = 0.42, p = 0.004 and 0.25°: r = 0.52, p = 0.002). CONCLUSIONS: Amblyopic eyes showed reduced pattern VEP amplitudes and delayed peak times with significant associations with the foveal sensitivity. However, the VEP measures overlapped extensively between amblyopic and control eyes with no apparent criterion value for optimal discrimination, suggesting that foveal sensitivity might be a better discriminator of amblyopia than pattern VEP.

Role of choroidal thickness assessment in unilateral acute anterior uveitis.

Purpose: The aim of our study was to investigate the change in the subfoveal choroidal thickness in unilateral acute anterior uveitis with treatment. Choroidal inflammation is uncommon but can occur in the acute stage of anterior uveitis. Methods: All diagnosed patients with the first episode of unilateral acute anterior uveitis were included in the study conducted for a period of July 2017-July 2018. Choroidal thickness at subfoveal region was measured with spectralis spectral domain optical coherence tomography using enhanced depth-imaging scans. Standardized, masked manual measurement of the choroidal thickness was performed in the center of the ETDRS fields. The unaffected fellow eye of the same patient was taken as a control group and their subfoveal choroidal thickness was measured. Follow up of the patients was done at 2 weeks posttreatment to reevaluate the choroidal thickness. Results: A total of 61 eyes of 61 patients with unilateral acute anterior uveitis were included in the study. The mean central subfoveal choroidal thickness was significantly higher (304.82 ± 73.17 µm) as compared to that of controls (251.28 ± 66.38 µm) at presentation (P < 0.001). Following treatment and at two weeks follow up, the subfoveal choroidal thickness significantly reduced from 304.82 ± 73.17 to 274.46 ± 63.82 µm (P < 0.001). Also the subfoveal choroidal thickness was positively correlated with visual acuity (r = 0.22, P < 0.251) before treatment. Conclusion: Acute anterior uveitis is associated with an increase in the subfoveal choroidal thickness followed by the significant decrease in choroidal thickness with treatment, suggesting that choroid is also inflamed along with anterior segment inflammation.

Perinatal Risk Factors for Retinopathy of Prematurity in Preterm and Low Birth Weight Neonates.

BACKGROUND: Retinopathy of prematurity (ROP) is emerging as a leading cause of childhood blindness. The incidence of ROP is likely to increase after improvement in neonatal care unit in premature neonates. This study is conducted to determine the perinatal risk factors for ROP in preterm and low birth weight neonates. METHODS: This is a prospective, descriptive and clinical; hospital based study. A total of 92 preterm neonates with gestational age of 36 weeks or less and birth weight of 2000 grams or less admitted in Neonatal Intensive Care Unit (NICU) were screened. Detailed antenatal, perinatal and neonatal history; birth asphyxia and subsequent oxygen support records were noted. All the neonates underwent detailed anterior and posterior segment eye examination with indirect binocular ophthalmoscope after pupil dilatation within 4 weeks of life. Retinal vascular changes were classified according to the International Classification of Retinopathy of Prematurity. The Chi-square test with odds ratio was performed to derive the association between ROP and antenatal, perinatal and neonatal factors. A p-value was considered significant at 0.05. RESULT: Out of 92 neonates, 21(22.8%) developed ROP. Twelve neonates (13%) had stage-1 ROP, 6(6.5%) had stage-2 and 3(3.3%) had stage-3 ROP. Birth weight (OR=2.9; p=0.04; 95% CI=1.0-8.3), gestational age (OR=3.9; p=0.01; 95% CI=1.3-11.8) and time span of oxygen exposure (OR=2.9; p=0.05; 95% CI=1.0-8.4) had a strong association with ROP. CONCLUSION: The incidence of ROP is significantly high among preterm low birth weight neonates. The risk of developing ROP becomes even greater with lower gestational age and more duration of oxygen exposure.

Flash VEP in clinically stable pre-term and full-term infants.

PURPOSE: Pre-term infants are at risk of abnormal visual development that can range from subtle to severe. The aim of this study was to compare flash VEPs in clinically stable pre-term and full-term infants at 6 months of age. METHODS: Twenty-five pre-term and 25 full-term infants underwent flash VEP testing at the age of 6 months. Monocular VEPs were recorded using flash goggles on a RETIscan system under normal sleeping conditions. Amplitude and peak time responses of the P2 component in the two eyes were averaged and compared between the two groups. Multiple regression analyses were performed to assess the relationship of the P2 responses with birth weight (BW) and gestational age (GA). RESULTS: At 6 months corrected age, pre-term infants had significantly delayed P2 peak times than full-term infants (mean difference: 10.88 [95% CI 4.00-17.76] ms, p = 0.005). Pre-term infants also showed significantly reduced P2 amplitudes as compared to full-term infants (mean difference: 2.36 [0.83-3.89] µV, p = 0.003). Although the regression model with GA and BW as fixed factors explained 20% of the variance in the P2 peak time (F2,47 = 5.98, p = .0045), only GA showed a significant negative relationship (ß = -2.66, p = .003). Neither GA (ß = 0.21, p = .28) nor BW (ß = 0.001, p = .32) showed any relationship with P2 amplitude. CONCLUSIONS: Our results demonstrate that, compared with full-term infants, clinically stable pre-term infants exhibit abnormal flash VEPs, with a delay in P2 peak time and a reduction in P2 amplitude. These findings support a potential dysfunction of the visual pathway in clinically stable pre-term infants as compared to full-term infants.

Awareness of Eye Health and Diseases among the Population of the Hilly Region of Nepal.

PURPOSE: To collect information regarding awareness and knowledge of eye health and diseases among the population of the hilly region of Nepal. METHODS: In a population-based survey, 1834 participants were enrolled in to the study. Field procedures included the development of a survey questionnaire, field orientation, pretesting, and household data collection. Association between knowledge of eye diseases was derived using the Chi-square test and odds ratios with a 95% confidence interval. A P value of ≤0.05 was considered significant. RESULTS: Most participants were 31-40 years old (33.4%), female (51.1%), of upper caste (43.4%), Hindus (83.3%), received secondary level of education (34.4%), and involved in agriculture (48.6%). Awareness of cataract, night blindness, glaucoma, strabismus, and systemic diseases was 74.6%, 53.4%, 17.4%, 70.8%, and 46.5%, respectively. Knowledge regarding these diseases among those aware was 39.1%, 72.2%, 50.9%, and 92.3%, respectively. Awareness of cataract was significantly higher (88.4%) among higher caste groups (P < 0.001; OR, 4.29; 95% CI, 3.34-5.54), followed by business as an occupation (88.2%; P = 0.001; OR, 2.65; 95% CI, 1.44-4.9). Awareness of night blindness was significantly higher among students (72.6%; P < 0.001; OR, 2.46; 95% CI, 1.65-3.67). CONCLUSION: There was a general lack of awareness and knowledge of common eye diseases. Improved awareness and knowledge are required for the prevention, early treatment, and access to eye care.

Orbital Teratoma: A rare congenital tumour.

BACKGROUND: Orbital teratomas are congenital, unilateral germ cell tumors, which are present at birth with moderate to massive proptosis. The rare tumour has to be managed individually and is at times difficult. CASE: A female child in her 2nd day of life was brought to our department with complains of forward bulging of the left eye which was noticed since the time of her birth. OBSERVATION: Examination and investigations revealed a mass with scattered foci of calcification. The mass was causing expansion of left orbit with thinning and scalloping of bony boundaries of left orbit with no intracranial component. The scan suggests the diagnosis of orbital teratoma which was further confirmed by histopathological examination. CONCLUSION: The rare tumour presents a challenge in management. The aim of management depends upon the extent of tumour, preservation of vision whenever possible, promotion of normal orbital growth and cosmesis.

Macular thickness and macular volume measurements using spectral domain optical coherence tomography in normal Nepalese eyes.

PURPOSE: To record the normative values for macular thickness and macular volume in normal Nepalese eyes. METHODS: In all, 126 eyes of 63 emmetropic subjects (mean age: 21.17±6.76 years; range: 10-37 years) were assessed for macular thickness and macular volume, using spectral domain-optical coherence tomography over 6×6 mm(2) in the posterior pole. A fast macular thickness protocol was employed. Statistics such as the mean, median, standard deviation, percentiles, and range were used, while a P-value was set at 0.05 to test significance. RESULTS: Average macular thickness and total macular volume were larger in males compared to females. With each year of increasing age, these variables decreased by 0.556 µm and 0.0156 mm(3) for average macular thickness and total macular volume, respectively. The macular thickness was greatest in the inner superior section and lowest at the center of the fovea. The volume was greatest in the outer nasal section and thinnest in the fovea. The central subfield thickness (r=-0.243, P=0.055) and foveal volume (r=0.216, P=0.09) did not correlate with age. CONCLUSION: Males and females differ significantly with regard to macular thickness and macular volume measurements. Reports by other studies that the increase in axial length reduced thickness and volume, were negated by this study which found a positive correlation among axial length, thickness, and volume.

Burden of ocular and visual disorders among pupils in special schools in Nepal.

OBJECTIVES: To determine detailed oculo-visual characteristics of children with intellectual disability studying in special schools and explore the burden of visual impairment. DESIGN OF THE STUDY: Detailed ophthalmic examination was carried out in all pupils studying at the seven special needs schools of Kathmandu valley, Nepal. Ophthalmic examination included case history, presenting distance visual acuity, cycloplegic refraction, binocular vision examination, contrast sensitivity and anterior and posterior segment evaluation. MAIN OUTCOME MEASURES: Ocular and visual status of children. RESULTS: Refractive errors (40%) and strabismus (17%) were the commonest visual disorders in our study children. Ninety-five per cent of the children who had clinically significant refractive errors presented without any correction. Visual impairment was present in 25% of the children. Severe visual impairment or worse was present in 3% of the children. Other common ocular findings were conjunctivitis, blepharitis, chalazion and ectropion. CONCLUSIONS: High prevalence of preventable visual impairment in this population requires immediate attention. It is hoped that the formulation of proper vision care guidelines at a national level may help in early detection and management of visual disorders in this special population and enhance their quality of life.

A case of transorbital intracranial injury presenting with subtle neurological deficit.

BACKGROUND: Ocular trauma is a major cause of visual morbidity. OBJECTIVE: To present a rare case of transorbital intracranial injury extending up to the left internal carotid artery (ICA) with no other systemic neural deficit except for the ocular manifestations. CASE: A 14-year-old female presented to our out-patient department (OPD) with the history of trauma to her left eye with stumps of bamboo shoots secondary to a fall injury. Examination and investigations revealed a foreign body extending from left inferior conjunctival fornix into the intracranial cavity, occluding the various segments of left ICA. The patient subsquently underwent craniotomy and foreign body removal by a combined team of neurosurgeons and ophthalmologists. On discharge, the patient had slight improvement in extraocular motility of her left eye. However the trauma rendered the affected eye, non-seeing. CONCLUSION: The intracranial extent of a foreign body entering the cranium via the transorbital route cannot be judged merely by the clinical findings of the nervous system and ocular examination. These patients need timely management by the combined effort of ophthalmologists, neurosurgeons and radiologists.

Marfan's syndrome: a refractive challenge for optometrists.

We present an interesting case of a child with Marfan's syndrome with ectopia lentis, who was followed for five years. The changes in refractive and visual findings of this child during this period are discussed. The importance of careful oculo-visual examination and possible management options in such children are highlighted.

Causes of blindness and visual impairment among students in integrated schools for the blind in Nepal.

PURPOSE: To identify the causes of blindness and visual impairment among students in integrated schools for the blind in Nepal. METHODS: A total of 778 students from all 67 integrated schools for the blind in Nepal were examined using the World Health Organization/Prevention of Blindness Eye Examination Record for Children with Blindness and Low Vision during the study period of 3 years. RESULTS: Among 831 students enrolled in the schools, 778 (93.6%) participated in the study. Mean age of students examined was 13.7 years, and the male to female ratio was 1.4:1. Among the students examined, 85.9% were blind, 10% had severe visual impairment and 4.1% were visually impaired. The cornea (22.8%) was the most common anatomical site of visual impairment, its most frequent cause being vitamin A deficiency, followed by the retina (18.4%) and lens (17.6%). Hereditary and childhood factors were responsible for visual loss in 27.9% and 22.0% of students, respectively. Etiology could not be determined in 46% of cases. Overall, 40.9% of students had avoidable causes of visual loss. Vision could be improved to a level better than 6/60 in 3.6% of students refracted. CONCLUSION: More than one third of students were visually impaired for potentially avoidable reasons, indicating lack of eye health awareness and eye care services in the community. The cause of visual impairment remained unknown in a large number of students, which indicates the need for introduction of modern diagnostic tools.

Optical needs of students with low vision in integrated schools of Nepal.

PURPOSE: To identify the optical needs of students with low vision studying in the integrated schools for the blind in Nepal. METHODS: A total of 779 blind and vision-impaired students studying in 67 integrated schools for the blind across Nepal were examined using the World Health Organization/Prevention of Blindness Eye Examination Record for Children with Blindness and Low Vision. Glasses and low-vision devices were provided to the students with low vision who showed improvement in visual acuity up to a level that was considered sufficient for classroom learning. Follow-up on the use and maintenance of device provided was done after a year. RESULTS: Almost 78% of students studying in the integrated schools for the blind were not actually blind; they had low vision. Five students were found to be wrongly enrolled. Avoidable causes of blindness were responsible for 41% of all blindness. Among 224 students who had visual acuity 1/60 or better, distance vision could be improved in 18.7% whereas near vision could be improved in 41.1% students. Optical intervention provided improved vision in 48.2% of students who were learning braille. Only 34.8% students were found to be using the devices regularly after assessment 1 year later; the most common causes for nonuse were damage or misplacement of the device. CONCLUSIONS: A high proportion of students with low vision in integrated schools could benefit from optical intervention. A system of comprehensive eye examination at the time of school enrollment would allow students with low vision to use their available vision to the fullest, encourage print reading over braille, ensure appropriate placement, and promote timely adoption and proper usage of optical device.

Visual defects in Nepalese children with Down syndrome.

BACKGROUND: Down syndrome (DS) is a common chromosomal anomaly. People with this syndrome have recognisable physical characteristics and limited intellectual abilities. The aim of this study was to determine visual defects, especially refractive error and binocular anomalies, in a sample of Nepalese children with DS. METHODS: Thirty-six children with DS (19 boys and 17 girls) from the Kathmandu valley, aged from four months to 18 years, underwent detailed optometric examination. Cycloplegic refraction was performed on all subjects. Vision on presentation of all the children was assessed with preferential looking cards, the Kay picture cards, the Bailey-Lovie logMAR chart or the Snellen chart. Binocular function was assessed with cover test, Hirschberg or Bruckner test. RESULTS: Cycloplegic refraction of the children revealed that 80 per cent of the children had significant refractive error. Most of them had hyperopia (55 per cent), followed by astigmatism (44 per cent), myopia (25 per cent) and anisometropia (19 per cent). Only two (5.6 per cent) children were strabismic and both of them were alternating esotropes. Nystagmus was present in 10 (28 per cent). Other ocular findings were upward slanting palpebral fissures, blepharitis, congenital nasolacrimal duct obstruction, blepharoconjunctivitis, chalazion and lenticular opacities. CONCLUSION: Nepalese children with DS have a high prevalence of refractive error and nystagmus. Regular eye examinations are indicated for these children to enable early diagnosis and appropriate management of ocular disorders to improve their vision and quality of life.

Incidence of retinopathy of prematurity in a neonatal intensive care unit in Nepal.

PURPOSE: To determine the incidence of retinopathy of prematurity (ROP) in low birth weight premature infants admitted to the neonatal intensive care unit of a children's hospital in Kathmandu. METHODS: A hospital-based prospective study was performed in neonates with a gestational age of less than 36 weeks or birth weight of less than 2,000 g during 1 year. Ophthalmologic examination was performed 2 to 4 weeks after birth and patients were observed until the retinal vascularization was complete. ROP was classified using the revised International Classification of Retinopathy of Prematurity. RESULTS: A total of 78 infants fulfilled the screening criteria. ROP was detected in 29.5% (n = 23) of neonates. Thirteen infants (16.7%) had stage 1 disease and 5 each (6.4%) were found to have stage 2 and stage 3 ROP. Threshold disease was present in 3.8% (n = 3) of infants with a gestational age of less than 32 weeks and birth weight less than 1,500 g who required laser treatment per Early Treatment of ROP criteria. Low birth weight (P < .01) and low gestational age (P < .01) were significantly associated with the incidence of ROP. CONCLUSION: Prematurity and low birth weight were found to be major risk factors for ROP. ROP screening should be performed in such infants for early detection because its incidence is likely to increase as more premature infants survive with improved neonatal care.