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CASE REPORT
Year : 2017  |  Volume : 4  |  Issue : 1  |  Page : 15-19

Optic nerve head disorders in a hilly state of india: a retro/prospective study


1 Department of Ophthalmology, Dr. Yashwant Singh Parmar Government Medical College, Nahan, Sirmaur, Himachal Pradesh, India
2 Department of Ophthalmology, Indira Gandhi Medical College, Shimla, Himachal Pradesh, India

Date of Web Publication20-Apr-2017

Correspondence Address:
Anubhav Chauhan
Senior Resident, Department of Ophthalmology, Dr. Yashwant Singh Parmar Government Medical College, Nahan, Sirmaur, Himachal Pradesh
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/2347-5617.204835

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  Abstract 

Aim: To study the pattern/distribution of optic nerve head disorders in the hilly terrain of Himachal Pradesh (altitude ranging from 500 to 4500 m above sea level). Subjects and Methods: It is a retro/prospective study of patients with retinal diseases attending the general ophthalmology clinic of a tertiary care facility at Shimla from August 2008 to April 2013. Out of 5600 patients, 4323 were taken as a sample. The data were taken from the hospital records and thereafter analyzed to determine their age, sex distribution, and diagnosis. All patients underwent visual acuity, refraction, slit lamp examination, and fundus evaluation. The diagnosis was confirmed from fundus clinic records and evaluation of fundus photographic records retroprospectively. The photographs were taken on the fundus camera (KOWA'S FUNDUS CAMERA VX-10) and fundus fluorescein angiography done where ever indicated. Using the inbuilt software in KOWA VX 10 FUNDUS CAMERA, cup-disc ratio calculation was done. Results: Among the 139 (3.24%) patients of congenital optic nerve head disorders, the most common entity was optic nerve head hypoplasia. Out of 248 (5.73%) cases of acquired optic nerve head disorders-nonglaucomatous (NG), optic atrophy-NG was the most common. There were 532 (12.31%) cases of glaucoma suspects. Conclusion: Optic nerve head disorders appear to be a major public health problem in India as well as Shimla hills. The present study shall help us in planning the management of such disorders in the hilly state of Himachal Pradesh to reduce the visual morbidity arising out of such disorders.

Keywords: Himachal Pradesh, optic nerve, retroprospective


How to cite this article:
Chauhan A, Chaudhary KP, Rajput GC. Optic nerve head disorders in a hilly state of india: a retro/prospective study. Egypt Retina J 2017;4:15-9

How to cite this URL:
Chauhan A, Chaudhary KP, Rajput GC. Optic nerve head disorders in a hilly state of india: a retro/prospective study. Egypt Retina J [serial online] 2017 [cited 2017 Jun 23];4:15-9. Available from: http://www.egyptretinaj.com/text.asp?2017/4/1/15/204835


  Introduction Top


Vitreoretinal diseases are one of the more common ocular morbidities leading to blindness in the adult population while being the most common cause of blindness worldwide in children. Population-based studies reported an overall prevalence of vitreoretinal disorders of 8.56%, with a range between 10.4% and 21.02% for the 40 years and over age group.[1] According to the Pakistan National Survey for blindness and visual impairment done in the year 2002–2003, posterior segment diseases accounted for 3.4% of total blindness and visual impairment.[2] The management of posterior segment disorders presents peculiar diagnostic and therapeutic challenges, especially in the resource deficient third world settings, due to scarcity of requisite human and material resources.[3]

Unlike the affections in anterior segment of the eye, the diseases affecting retina are mostly irreversible and often sight threatening.[4] A study found that retinal disorders are an important cause of blindness in India. It is estimated that there will be 244 million people (14.9% of the population) 65 years and older by 2050 compared with 42 million (4.5% of the population) people in 1995. This shift in demographics is likely to be accompanied by a shift in the prevalence of retinal diseases as major causes of blindness in India.[5]

Congenital optic nerve head anomalies are structural malformations of the optic nerve head which can lead to congenital visual impairment and blindness.[6] Optic neuritis (ON) is an inflammatory condition affecting the optic nerve. Regions with the highest incidence include northern Europe, southern Australia, and middle part of North America. It is reported to have an incidence of 1–5 cases per 100,000/year; higher the latitude, higher was found to be the incidence of optic neuritis.[7]

The most common cause of optic disc swelling in Caucasians has been reported to be anterior ischemic optic neuropathy.[8] The prevalence rate of nonarteritic anterior ischemic optic neuropathy (NAAION) in Chinese population >40 years was 1 in about 4500,[9] whereas in the United States, it was 2.3–10. Three patients per 100,000 inhabitants >50 years old per year.[10] A few epidemiological studies of idiopathic intracranial hypertension (IIH) show the incidence of the disease as 1–3/100,000/year.[11]

Glaucoma affects more than 67 million people worldwide, of whom about 10% or 6.6 million are estimated to be blind. Glaucoma is the leading cause of blindness worldwide and is second only to cataract as the most common cause of blindness overall.[12]

In this retro/prospective study of retinal diseases at a tertiary care facility of Shimla hills, we determined the pattern of optic nerve head disorders among the patients who reported for photographic evaluation. After undergoing extensive literature search on the internet, this is probably thefirst of its kind study where the pattern/incidence of all the optic nerve head disorders in a particular region has been carried out.


  Subjects and Methods Top


Subjects

The present study was conducted in the Department of Ophthalmology, Indira Gandhi Medical College, Shimla. Shimla is the capital of Himachal Pradesh which has 12 districts. A total of 5600 patients from all districts of Himachal Pradesh visiting the fundus clinic of a tertiary care institute were evaluated during a period from August 2008 to April 2013. From these 5600 patients, 4323 patients were taken as a sample. It is a retrospective and prospective study. We confirm adherence to the guidelines of the Declaration of Helsinki as well as Indira Gandhi Medical College Hospital Ethics Committee Approval.

Methods

In brief, the present study involved 4323 patients residing in Himachal Pradesh (altitude ranging from 500 to 4500 m above sea level). Himachal Pradesh is a hilly terrain and has a very distinct population that is composed of ethnolinguistic groups of tribals and socials. Most of the natives belong to Aryan origin while the people of Lahaul and Spiti district are essentially descendants of Mongols. Patients coming from all districts of Himachal Pradesh underwent visual acuity, refraction, slit lamp examination, and pupil dilatation for detailed fundus evaluation. The diagnosis was confirmed from hospital records, fundus clinic records, and evaluation of fundus photographic records retroprospectively. Inclusion criteria included proper and complete records of the patient with clear fundus photographs and fundus fluorescein angiography (FFA), whereas exclusion criteria included fundus photographs/FFA taken on fundus camera not clearly visible for making a diagnosis and patients presenting with opaque ocular media. Using the inbuilt software in KOWA VX 10 Fundus Camera, cup-disc (CD) ratio calculation was done. Glaucoma suspects were those patients with CD ratio of 0.6 or more, a vertical CD ratio larger than the horizontal CD ratio, optic disc hemorrhages (ODHs) and a disparity of more than 0.2 between the CD ratio of the two eyes. They were further subject to other investigations to rule out glaucoma.

In all the patients, ophthalmological examination was performed. Visual acuity was measured using Snellen chart, slit lamp biomicroscopy was done to assess the ocular adnexa and the anterior segment of eye using a slit lamp biomicroscope (Haag Striet-900). Fundus examination was done using the direct and indirect ophthalmoscope.

Fundus photographs were taken on the Fundus Camera (KOWA'S Fundus Camera VX-10, KOWA Company Ltd., 4–14, Nihonbashi-honcho 3-chome, Chuo-ku, Tokyo 103-8433 Japan). The patient was instructed to be seated in front of the fundus camera. Height of the optical bench was adjusted to let the chin on the chin rest and forehead on the forehead rest in a natural posture. The examined eyes were set at the eye level mark. Fundus camera was positioned such that the luminous spots for alignment can come in the center, and the luminous spot is smallest and sharpest. Then, by pressing the shutter button for photographing, the images taken were displayed on the monitor.

Fluorescein angiography was performed by injecting a 6 s bolus injection of 2–5 cc of sodium fluorescein into a vein in the arm or hand. A series of black-and-white or digital photographs were taken of the retina before and after the fluorescein reaches the retinal circulation (approximately 10 s after injection). Photos were taken approximately once every second for about 20 s, then less often. A delayed image was obtained at 5 and 10 min. A filter was placed in the camera, so only the fluorescent, yellow-green light (530 nm) was recorded.

Statistical analysis

Data collected were managed on an excel spreadsheet. Significance was determined using percentage.


  Results Top


During the period from August 2008 to April 2013, 5600 patients visiting the fundus clinic of the tertiary care institution were evaluated. From these 5600 patients, 4323 patients were taken as a sample for the study. Since the study was aimed to find out the pattern of optic nerve head disorders, other retinal disorders were not included in the study. [Table 1] shows that of the total 4323 cases studied; there were more males 2563 (59.28%) than females 1760 (40.72%) with fundus diseases.
Table 1: Gender distribution of cases

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[Table 2] reveals that among the 139 (3.24%) patients of optic nerve head disorders-congenital, optic nerve head hypoplasia (ONHY) was present in 37 (0.86%), morning glory in 5 (0.12%), choroid coloboma in 22 (0.51%), optic disc coloboma in 9 (0.21%), optic disc pit in 2 (0.05%), tilted disc in 25 (0.58%), optic disc drusen in 2 (0.05%), myopic disc in 21 (0.49%), and hypermetropic disc in 16 (0.37%) patients.
Table 2: Optic nerve head disorders-congenital

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[Table 3] shows that there exists 248 (5.73%) patients of acquired optic nerve head disorders-nonglaucomatous (NG) out of which optic atrophy-NG was present in 161 (3.72%), NAAION in 2 (0.05%), IIH-papilledema (IIH-papilledema) in 46 (1.06%), diabetic papillopathy in 1 (0.02%), ON in 33 (0.76%), optociliary shunts in 3 (0.07%), and pseudopapilledema in 2 (0.05%) patients.
Table 3: Acquired optic nerve head disorders-nonglaucomatous

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[Table 4] shows that acquired optic nerve head disorders-glaucoma suspects exist in 532 (12.31%) patients. ODHs were seen in 5 (0.93%) out of 532 cases.
Table 4: Acquired optic nerve head disorders-glaucoma suspects

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  Discussion Top


Although Himachal Pradesh is a hilly terrain consisting of different districts, the different districts having different types of geographic and socioeconomic conditions. Most of the people depend on agriculture as a source of income. There are many rural and backward areas. There is a diversity of culture, language, customs, food habits, and way of life. Yet, our study represents the patients residing in Himachal Pradesh. This is thefirst fundus photograph-based study to report the prevalence of vitreoretinal disorders in Himachal Pradesh. In the present study, more number of male patients with fundus diseases was seen as compared to females. These results are similar to the studies carried out by Eze et al., Karki et al., Teshome, and Oluleye and Ajaiyeoba.[3],[4],[13],[14]

Congenital optic nerve defects account for about 15% of severe visual impairment or blindness in the United Kingdom: ONHY alone accounting for 12%.[15] ONHY is the most commonly found optic nerve head anomaly.[6] ONHY was the most frequently encountered congenital optic nerve head disorder in our study as well.

In a retrospective study on optic neuritis, females were the predominant group involved with the age of the patients ranging between 3 and 55 years plus 67.7% of the patients having unilateral ocular involvement.[16] In another study, 36 patients (52 eyes) were found to have ON (papillitis in 36 and retrobulbar neuritis in 16 eyes). The male to female ratio was 1.25:1. The mean age of the patients was 33.56 17.88 years.[17] Shrestha et al. carried out a study and found that a total of 33 eyes (75%) had papillitis and 11 eyes (25%) had retrobulbar optic neuritis. Male to female ratio was 2.18:1. The mean age at presentation was 31.20 17.07 years. Most of the cases were unilateral.[18]

In a study by Lim et al., 60% of the patients had anterior ON with papillitis, were idiopathic in 49.1%, and associated with multiple sclerosis (MS) in only 25.5%. Bilateral cases comprised 16.4% and were usually of the anterior variety and mostly idiopathic.[19] The medical records of 49 patients who experienced optic disc swelling between March 2008 and June 2009 were retrospectively reviewed. ON was identified in 15 patients (30.6%).[8] In a retrospectively study of 100 patients (66% female; age 18–74 years) diagnosed with unilateral ON between 2003 and 2009 in a Chinese province, ocular pain was noted in 40% and disc swelling in 48%. Periventricular plaques were found in 8% and MS in 6%.[20] Age distribution, sex predominance, unilateral/bilateral ocular involvement, and clinical characteristics of ON were not taken in our study. In our study, ON was present in 33 (0.76%) out of 4323 patients.

NAAION was the most common disorder (34.7%) that presented with optic disc swelling in a study carried out by Jung et al.[8] In our study, it was one of the least common entities. Of the 8876 eyes included in a study, only one eye fulfilled the definition of NAAION.[9] The findings of this study closely matched our study though the difference between the two studies might me due to the difference in the size of sample. You et al. suggested that NAAION may have an incidence of about one in 139 patients with crowded optic discs per 5 years, with a baseline age of 54.3 8.7 years.[21] Age distribution was not taken in our study.

New cases of blindness occurring secondary to IIH were identified prospectively through the British Ophthalmological Surveillance Unit from October 2005 to November 2006. There were 12 definite cases of blindness secondary to IIH giving a United Kingdom incidence of blindness secondary to IIH of 0.6–2% (assuming a United Kingdom population of 63.2 million and an incidence of IIH of 1–3/100,000).[11] Forty-two patients were identified as having IIH corresponding to an average annual incidence rate per 100,000 persons of 0.5 for the total and 0.9 for the female population.[22]

A study was carried out by Carta et al. to ascertain the annual incidence of IIH in Italy and they concluded that ten patients had IIH, with age range from 16 to 53 years. The annual age-adjusted rate per 100,000 came out to be 0.28% for total population.[23] In another study, annual incidence of IIH in Sheffield, United Kingdom was carried out, and the result came out to be an incidence of 1.56/100,000/year.[24] Seven out of 49 patients (14.3%) had intracranially associated diseases.[8] In our study, IIH was present in 46 (1.06%) out of total 4323 patients. The annual incidence, age distribution, and associated complications of IIH were not taken in our study.

The overall rate of glaucoma and glaucoma suspects was 18.3% in a study.[25] Age adjusted prevalence rates for primary open angle glaucoma was different among different races.[26] In a study by Osaguona et al., ocular morbidity arising in glaucoma suspects was 17.4%.[27] ODH was detected on optic disc photographs in 16 (7.2%) of the 221 eyes with optic disc glaucoma and in 11 (8.2%) of the 134 eyes with perimetric glaucoma.[28] Prevalence of disc hemorrhages was 17/8869 per eye and 16/4570 per patient. Prevalence of disc hemorrhages (0.2% per eye; 0.4% per patient) in Indians aged 30 + years was strongly associated with glaucoma.[29]

The estimated prevalence of ODH in the Korean population aged 19 years and older was 0.42%. Prevalence of ODH in glaucomatous patients was 2.82%.[30] In our study, ODHs were seen in 5 (0.93%) patients. The difference between our study and the previous studies might me due to the difference in the size of sample. Ocular morbidity due to glaucoma and racial predilection was not taken in our study.

Pseudopapilledema was noted in four patients (8.2%).[8] In our study, it was seen in 2 (0.05%) cases. The difference could be due difference in sample size.


  Conclusion Top


Retinal disorders appear to be a major public health problem in India. The results of this study gave an insight into the prevalence of optic nerve head disorders. The present study shall help us in planning the management of such disorders in the hilly state of Himachal Pradesh to reduce the visual morbidity arising out of such disorders. This entails the necessity for accessible comprehensive eye care services, establishment of human resources, screening and awareness of the disease, and affordable eye health policy.

Acknowledgments

We would like to thank all the patients and Department of Ophthalmology, Indira Gandhi Medical College, Shimla, for their assistance and support.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
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    Tables

  [Table 1], [Table 2], [Table 3], [Table 4]



 

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