Comparison between the protective effect of Ophthalmic Viscoelastics on the corneal endothelium in phacoemulsification
Authors: Saleh S M A , Elghazawy R M F , Elawamry A I , Zaki R G 
Published: May 2020

Abstract

Background
Phacoemulsification is one of the most common surgical interventions done worldwide; the ultrasound power used to emulsify and remove the cataractous lens is hazardous to corneal endothelium and can lead to permenant damage. Thats why ophthalmic viscoelastics have been developed and used to protect the corneal endothelium and ensure safety of intraocualr surgeries.

Objective
To study the effect of different concentrations of methyl cellulose on the corneal endothelium during phacoemulsification using specular microscopy.

Patients and Methods
Sixty patients with Immature Senile Cataract (IMSC) are equally distributed into two groups according to the concentration of Hydroxypropyl Methylcellulose (HPMC) used during phacoemulsification. In the first group HPMC 2% was used and in the second group HPMC 2.4% was used. Preoperative and one month postoperative examination was done including visual acuity testing, slit lamp examination using Topcon SL-3C, intraocular pressure measurement using Goldmann Applanation Tonometer (GAT), fundus examination, corneal edndothelium assessment by Tomey Specular Microscope EM-3000.

Results
Preoperatively, no significant difference was observed in age, sex, visual acuity, introcular pressure and endothelial cell count among the two groups. Postoperatively, the two groups had a significant decrease in endothelial cell count, but the decrease was less in group 2 using Methyl cellulose 2.4% (13.494%) than in group 1 using Methyl cellulose 2% (14.515%).There was an equal and significant increase in visual acuity in the two groups.

Discussion
Many studies have been done to compare the efficacy of different viscoelastics (OVDs) in the protection of corneal endothelium during phacoemulsification. In our study we compared the protective effect of two different concentrations of HydroxyPropyl MethylCellulose (2% &2.4%) on the corneal endothelium during phacoemulsification. We compared the demographic data as regarding age and sex of the patients in the two groups, also we compared the preoperative endothelial cell count in the two groups using Specualr Microscopy and the result showed no significant difference between the 2 groups. The endothelial cell loss was comparable in the 2 groups, in group 1 it was 362.267 ± 52.020 (14.515 % ± 1.458) and in group 2 it was 335.667 ± 21.170 (13.494% ±0.667) with slightly better protection in the second group. So these results shows that HPMC 2.4% gives better protection than HPMC 2% on corneal endothelium during phacoemulsification on terms of the postoperative endothelial cell count and the endothelial loss after phacoemulsification. Many studies have been done to compare the efficacy and the protective effect of different viscoelastics during phacoemulsification for example the studies done by Miller et al, Maar et al, Vajpayee et al and Storr-Paulsen et al, these studies showed results similar to our study as regards the protective effect of methyl cellulose with its different concentrations on the corneal endothelium during phacoemulsification, so both concentrations (2% and 2.4%) can be used safely and effectively in phacoemulsification to decrease the endothelial loss and ensure patients safety.

Conclusion
Methyl cellulose 2.4% and Methyl cellulose 2% were comparable in their ability to protect the corneal endothelium during phacoemulsification, in general both viscoelastics can be efficiently and safely used in performing phacoemulsification.