Anu Joseph, (2017) A Comparative study of Increase in Central Corneal Thickness following Congenital Cataract Surgery in Pseudophakic and Aphakic Eyes. Masters thesis, Madurai Medical College, Madurai.
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Abstract
INTRODUCTION: A Congenital cataract is defined as any loss of transparency or opacification of the lens fibres present at birth. The incidence rate of paediatric cataracts in developing countries like India is high and 7.4-15.3% of childhood blindness is due to cataract. Although cataract extraction in children is performed at early ages to prevent stimulus deprivation amblyopia, other complications, such as secondary glaucoma, continue to threaten the visual outcome. The thickened cornea after congenital cataract extraction can lead to overestimation of Intra Ocular Pressure (IOP) readings. This can cause over diagnosis of aphakic glaucoma along with overuse of anti-glaucoma medications. Overestimation or underestimation IOP in these patients can have a significant impact on their treatment and overall prognosis. AIMS AND OBJECTIVES: 1. To determine the central corneal thickness in pseudophakics and aphakics following congenital cataract surgery in children. 2. To compare the central corneal thickness in pseudophakics and aphakics following congenital cataract surgery with age matched healthy controls. MATERIALS & METHOD: This is a comparative cross sectional study and the study was conducted among 32 post-operative cases of congenital cataract attending the OPD as well as wards of department of Ophthalmology as well as Institute of Paediatrics in Government Rajaji Hospital Madurai. Subjects are evaluated for entry into the study. Subjects who fulfilled all eligibility criteria, and none of the exclusion criteria, were recruited in our study. METHODOLOGY: 32 cases following congenital cataract surgery, including 19 aphakic eyes and 41 pseudophakic eyes were recruited for the study after obtaining consent from their guardians. Written informed consent was obtained from the parents / guardians of the cases recruited into the study. Visual acuity was recorded in cooperative children. A detailed evaluation of the anterior and posterior segment was carried out. Intra ocular pressure was recorded with the help of Goldmann applanation tonometry in cooperative children and hand held applanation tonometer in uncooperative small children. Central corneal thickness (CCT) measurements were taken with Ultrasonic pachymetry. After explaining the procedure, local anaesthetic drops (0.5% propararcaine) was instilled into the eyes. After 5 minutes, child is reassured and asked to fix at a distant target. CCT is measured by placing the tip of the probe gently on the centre of cornea. An average of 5 readings is taken. Uncooperative children were examined under sedation. RESULTS: A total of 32 post operative cases of congenital cataract were studied, which included 19 aphakic eyes and 41 pseudophakic eyes. The age distribution of cases and controls varied from 4-12 years majority being in the range between 6-8 years of age with a male preponderance. The age at which lensectomy was done in study group varied from 1-5 years, most of them being in the range of 2-3 years. The mean CCT of study group was found to be 583.50 μm ranging from 500-612 μm. The central corneal thickness in aphakic group ranged from 550 μm to 612 μm, mean value being 595.68 μm. The central corneal thickness in pseudophakic group ranged from 490 μm to 588 μm, mean value in primary pseudophakics being 521.42 μm and for secondary pseudophakics it was 554.62 μm. CCT was found to be higher in secondary pseudophakics when compared to their primary counterparts. The IOP values in the study group ranged between 12-32 mm of Hg, the mean IOP being 22.88 mm of Hg. There was a significant difference in CCT between the study group and control group. There was a significant positive correlation (r=0.525) between CCT and IOP in the study group. CONCLUSION: Children who have undergone lens extraction for congenital cataract are found to have a clinically significant increase in central corneal thickness which can in turn provide overestimated intraocular pressure readings by applanation tonometry. Aphakic eyes have a thicker cornea when compared to their pseudophakic counterpart showing primary lens implantation can be a protective factor against this increase. So measuring central corneal thickness should be made mandatory and necessary intra ocular pressure corrections made before prescribing antiglaucoma medications in children who are highly susceptible to their serious side effects.
| Item Type: | Thesis (Masters) |
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| Uncontrolled Keywords: | Congenital Cataract, Central Corneal Thickness, Aphakia, Posterior Continuous Curvilinear Capsulorrhexis. |
| Subjects: | MEDICAL > Ophthalmology |
| Depositing User: | Devi S |
| Date Deposited: | 19 Mar 2020 16:31 |
| Last Modified: | 19 Mar 2020 16:31 |
| URI: | http://repository-tnmgrmu.ac.in/id/eprint/12360 |
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