Visual outcome after ND: YA Glaser posterior capsulotomy in pseudophakic patient

Background: Posterior capsular opacification (PCO) also called as “after cataract” is a common complication following extra capsular cataract surgery with or without posterior chamber intraocular lens implantation.An opaque membrane develops as retained cells proliferate and migrate on the posterior capsular surface. Material and Methods: The study included a total of 100 eyes of 100 patients who were diagnosed to have posterior capsular opacification and were fulfilling all the inclusion and none of the exclusion criteria. After that they were taken for a detailed clinical examination. All patients underwent Nd: YAG laser capsulotomy and were followed up at 1 week, 1 month and at 3 months. At every follow-up detailed examination was done. BCVA and any complications were noted. Results: Of the 100 patients, 45 (45%) were male and 55 (55%) were female. Majority of the patients were in the age group 61-70 years. The average time interval between cataract surgery and Nd-YAG laser capsulotomy was between 2-4 years. In the type of PCO seen, 84 (84.0%) patients were having Elsching pearls type of PCO, 8 (8.0%) patients were having fibrous type of PCO and 8 (8.0%) patients were having Sommering ring type of PCO. The pre laser visual acuityin more than 62% of eyes was 6/60 to FC while 38% had visual acuity of 6/36 to 6/18. Visual acuity of 6/18 or better was achieved in 27% of eyes while 73% recovered to 6/12 to 6/6. None of these eyes showed further deterioration in visual acuity. The highest energy requirement was in the Fibrous PCO s0.89 ± 0.15 J, followed by Sommering Ring PCO 0.70 ± 0.17 J and least energy was in Elsching pearls 0.47 ± 0.24 J. The comparison of mean energy between the type of PCO was found to be statistically significant (P<0.05), showing that the mean energy was varying between the types of PCO. Conclusion: Neodymium-YAG capsulotomy for PCO is rewarding procedure inadults and has good visual outcome.


Introduction
Cataract is the main cause of avoidable blindness [1]. Despite some recent advances in the field of cataract potential drug treatments, surgery is still acknowledged to be the most effective treatment option [2]. Despite the meticulous surgery and removal of the cataractous lens, the lens epithelial cell stillposes a threat to the long-term outcome of the surgery. Postoperative opacification of initially clear posterior capsules occurs frequently in patients after the surgery. Time for opacification is highly variable varying from months to years in adults. The most convenient way of the Manuscript received: 20 th July 2018 Reviewed: 30 th July 2018 Author Corrected: 4 th August 2018 Accepted for Publication: 9 th August 2018 removal of the posterior capsule opacification is toclearing the visual axis by creating a central opening in the opacified posterior capsule using Nd -YAG laser [3]. It is a solid-state laser with a wave length of 1064 nm that can disrupt ocular tissues by achieving optical breakdown with a short, high-power pulseresulting in ionization, or plasma formation that causes acoustic and shock waves that disrupt tissue.
Contraindications to laser capsulotomy can be divided into absolute and relative. Corneal scars, irregularities, or edema that interfere with target visualization or make optical breakdown unpredictable and inadequate stability of the eye are absolute contraindications while glass intraocular lens, known or suspected cystoid macular edema, active intraocular inflammation, high risk for retinal detachment are relative contraindications.

Purpose
Primary: To study the visual outcome post capsulotomy after the cataract surgery Secondary: To assess the energy required in ND: YAG for different types of the PCO

Material and Methods
Consent from ethical committee for the study was taken. The procedures followed were in accordance with the ethical standards committee on human experimentation (institutional or regional) and with the Helsinki Declaration of 1975, as revised in 2000. The present study was a cross sectional study and included 100 patients attending outpatient Department of Ophthalmology from January 2017 to January 2018 and willing to provide their voluntary written informed consent. Consent from each patient was taken before the procedure.
Pre laser work up: Each patient was thoroughly evaluated with the help of slit lamp. Best corrected visual acuity (BCVA) was noted along with IOP. Both the pupils were dilated using a short acting mydriatic drug (0.8% tropicamide and 5% phenyephrine) and then the patient was made to sit for 30 minutes. After 30 minutes the dilatation of the pupil was assessed along with complete slit lamp examination. On slit lamp the type of PCO was assessedand 5-step photography was done, followed by fundus examination with VOLK 90D orindirect 20D lens.
Procedure: Topical anaestheticwas instilled in the eye tobe lasered. The patient was made to sit on ZEISS ND: YAG laser machine. The Abraham yag capsulotomy lens was fixed on the eye with the help of viscoelastic. The energy of the laser was fixed and then shots were taken and modified according to type of PCO.
Post laser work up and follow up: After the procedure, the patient was made to sit for 10 to 15 minutes. Post Yagprocedure topical beta blocker was instilled into the lasered eye and then the patient was asked to come for follow-up after 1 week.
The patient was sent home with a topical antibiotic drop along with a mild steroid (dexamethasone) to be instilled 4 times a day for 1 week.
Along with this a beta blocker was added to be instilled twice a day for 1 week. At 1 week follow-up the IOP and BCVA of the patient was recorded.
All the data was recorded in a customized proforma designed for the study purpose.

Results
In our study 100 patients were studied which included 55 (55.0%) females and 45 (45.0%) males, showing a female preponderance. There were 7 (7.0%) patients in the age group 30-40 years, 14 (14.0%) patients were in the age group 41-50 years, 31 (31.0%) patients were in the age group 51-60 years, 36 (36.0%) patients were in the age group 61-70, 10 (10.0%) patients were in the age group 71-80 years and 2 (2.0%) patients were in the age group >80 years.Majority of the patients were in the age group 61-70 years(36%). The mean age in Elsching pearls was 60.36 ± 11.46 years, in Fibrous it was 60.50 ± 10.66 years and in the Sommering Ring it was 56.75 ± 14.46 years. The comparison was found to be statistically not significant (P>0.05). There was comparable distribution of males and females in relation to type of PCO (P>0.05).
The time interval between cataract surgery and Nd-YAG laser capsulotomy was noted. 25 (25.0%) patients had duration from surgery from 1-2 years, 62 (62.0%) patients had duration from surgery from 2-4 years and 13 (13.0%) patients had duration from surgery of more than 4 years. Most of the patients had duration from surgery between 2-4 years (62%).

Discussion
Age and sex-A total of 100 patients were studied who presented with PCO post cataract surgery between the ages of 30 to those over 80 years, with most the patients 36% falling between the ages of 61-70 years. The sex distribution was a 55% female to 45% male ratio with female preponderance.
Opacification post-surgery-The Neodymium-YAG laser has become popular non-invasive technique of creating a posterior capsulotomy to create an opening in the posterior lens. Its safety and efficacy can be argued but it has established its place as a standard treatment for PCO replacing surgical capsulotomy. The time period between cataract extraction and performing Neodymium-YAG laser capsulotomy at average was 2-4 years in our study while it was reported as 2.49 years by Hasan et al [4], and 24 months in another study by Kundi NK et al [5]. Emery, Wilhelmus, and Rosenberg [6] found opacification in 28% of their patients with 2-3 years of follow-up. Late opacification of the posterior capsule after 3-5 years has been reported to be approximately 50%.

Conclusion
Nd: YAG laser capsulotomy is asafe and effective method to treat PCO. It is non-invasive and avoids all the complications associated with surgical capsulotomy such as endophthalmitis and wound related problems and local anaesthesia such as perforation and haemorrage etc. Majority of the patients were in the age group 61-70 years.
Elsching's pearls were present in maximum patients. Majority of patients had significant improvement in visual acuity with 73% having visual improvement between 6/6 to 6/12. There is a significant decrease in the overall Post YAG IOP in comparison to the overall Pre YAG IOP. Corneal oedema and iritis were seen as post laser complications.