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Year : 2016 | Volume : 4 | Issue : 4 | Page : 194 - 197  


Original Articles
Efficacy of manual small incision cataract surgery in preventing the endothelial cell loss

Nanda Kumar Reddy PV 1, Sunisha 2, Atul Gupta 3

1 Professor and HOD, Department of Ophthalmology, Malla Reddy Medical College for Women, Hyderabad

2 Senior Resident, 3 Assistant Professor, Department of Ophthalmology, Sarojini Devi Eye Hospital, Hyderabad

Corresponding Author:

Dr. P.V. Nanda Kumar Reddy

Email: drnkreddyperur@gmail.com.

ABSTRACT:

Background: Every year 5 million cataract surgeries are performed in India. Two major procedures are used to conduct cataract operations either MSICS/Phecoemulisfication. In both the procedures the loss of endothelial cells are observed. The present study is based on comparison of endothelial cell loss in both the procedures.

Objectives: The aim of the study is to compare endothelial cell loss after manual small incision cataract surgery (MSICS) and phacoemulsification by specular microscopy.

Methods: Present study was conducted at Sarojini Devi Eye Hospital, Hyderabad from 2013-14. Total number of eyes studied was 100 in 100 study subjects who were age and sex matched and divided into two groups of 50 eyes of 50 study population. Group I patients underwent Phaecoemulsification & Group II with MSICS by the same operating surgeon from 2013-14. The patients were evaluated on first post operative day, first week, 6 weeks and 6 months for endothelial density. Endothelial density was evaluated through Specular Microscopy EM 3000, Tomey. Best image of 15 shots was taken to evaluate endothelial density.

Results: Mean age in both the groups was 58 and 59 years. Equal number was taken sex wise in both the groups. The mean endothelial loss was 200 cells/mm2 & 250 cells/mm2 in Group I & II respectively.

Conclusions: In phacoemulsification group, the maneuvering was performed in the capsular bag and newer advanced phacoemulsification units with better fluidics reduced the chances of endothelial damage. In MSICS group, Visco-expression of the nucleus significantly reduced the endothelial cell loss.

Key Words: Pachymetry, Phaecoemulsification, Specular Microscopy

 

INTRODUCTION:

The mean endothelial density (ECD) in the normal adult cornea ranges from 2000 to 2500 cells/mm2, and the count continues to decrease with age. 1, 2 Morphological stability and functional integrity of the corneal endothelium are necessary to maintain long-term corneal transparency after cataract surgery. Endothelial cell loss and corneal decompensation after cataract surgery is well-documented. All surgical procedures that involve entry into the anterior chamber damage a proportion of endothelial cells intra-operative corneal manipulation. After endothelial cell loss, the adjacent cells enlarge and slide over to maintain endothelial cell continuity, which is observed as a change in the endothelial cell density and morphology. Moderate damage to the endothelium during surgery can also lead to a transient increase in corneal thickness. 3, 4 Endothelial cell density and function can be assessed clinically using specular microscopy and pachymetry.

In developing countries such as India, where there is a cataract backlog, MSICS with intraocular lens (IOL) implantation promises to be a viable cost-effective alternative to phacoemulsification. In India, approximately 5 million cataract surgeries are performed per year 5, 6; therefore, it is important to determine the safest surgical technique for the endothelium. There is a paucity of data from India on the effect of small-incision cataract surgery (SICS) and phacoemulsification on the corneal endothelium was performed to assess the postoperative endothelial cell loss and change in endothelial morphology over a short period of time between the two commonly performed cataract techniques. This study aims at comparing the Endothelial cell loss after manual small incision cataract surgery ( MSICS ) and phacoemulsification by specular microscopy.

MATERIAL & METHODS:

Inclusion criteria:

100 patients of age > 40 years with senile cataract of NS Gr II and NS Gr III

Exclusion Criteria:

  • Traumatic cataract.
  • Complicated cataract.
  • Corneal diseases (Fuchs dystrophy)
  • Other causes of decreased vision (Diabetes, Glaucoma)
  • Intra-operative posterior capsular rupture and vitreous loss

Prospective Observational Study

Study Duration: January 2013 - August 2014

Set - up: Sarojini Devi Eye Hospital, Hyderabad

Study Design:

The study population consisted of 100 eyes of 100 patients who were age matched and sex matched was divided into two groups. 50 eyes were included in each group. All the patients underwent complete ophthalmic examination with Slit Lamp Examination, Gonioscopy and endothelial cell density by Specular Microscopy EM 3000, Tomey. Group I patients underwent phacoemulsification and Group II underwent Manual Small Incision Cataract Surgery (MSICS) by same surgeon during period of January 2013 to August 2014 at Sarojini Devi Eye Hospital, Hyderabad. The patients were evaluated by specular microscopy for endothelial cell density postoperatively on 1st postoperative day, 1 week postoperative, 6 week postoperative and 6 months postoperative. 5, 6

Image Analysis

In the study endothelial cell density is measured by EM 3000, Tomey. 15 shots are taken in series and best image among 15 images is automatically selected and displayed on screen. The software for automatic analysis is pre installed and image is analyzed automatically.

Figure I: Image Analysis

Statistical Analysis:

All data obtained were recorded and presented as mean with standard deviation. Student paired T - test was used on all continuous data to calculate statistical significant difference between preoperative and postoperative values within same group. Student unpaired T - test was used to calculate the statistical significant difference between different group values. The statistical significance is taken when p - value < 0.05.

RESULTS:

Present Study included 50 patients who underwent phacoemulsification (Group 1) and 50 patients who underwent MSICS (Group 2) by the same surgeon. The mean age of Group I was 58 years (95% Confidence interval; 55 - 61 years) 59 years [95% confidence interval: 54 - 64 years) and for Group II. There was no statistically significant difference in age between groups (p-value - 0.3320).

In the study 25 males and 25 females in each group were included.There was no statistically significant differance in sex distribution between Group I and Group II.(p - value : 1.0 )

In the study , 23 patients had NS Gr II ( 46 % ) and 27 patients had NS Gr III ( 54 %) in each group were included. There was no statistically significant difference in lenticular opacity distribution between Group I and Group II ( p - value - 1.00 )

The mean preoperative endothelial cell density was 2575 cell/mm2(95% CI: 2285 - 2866) in Group I and 2535 cell/mm2(95% CI: 2274 - 2895) in Group II .There was no statistically significant in preoperative ECD between Group I and Group II. (P = 0.8397).

The 100 patients were undergone cataract surgery, i.e. 50 patients in Group I underwent phacoemulsification and 50 patients in Group II underwent MSICS by same surgeon. Endothelial Cell Density was calculated postoperatively on day 1, 1 week and 6 weeks and 6 months by EM 3000, Specular Microscope .Comparison of mean ECL was done between two groups. The mean endothelial cell loss on first postoperative day in Group I was 266 Cells/mm2 ( 95 % confidence interval - 243 - 289 ) and in Group II was 273 Cells/mm2 ( 95% confidence interval - 240 - 306 ).There was no statistically significant difference of mean ECL between Group I and Group II on first postoperative day( p - value 0.6578 )

The mean endothelial cell loss at 1 week in Group I was 200 Cells/mm2 ( 95 % confidence interval -190 to 210 ) and in Group II was 250 Cells/mm2 ( 95% confidence interval - 230 to 270 ) .There was no statistically significant difference of mean ECL between Group I and Group II at 1 week postoperative ( P value - 0.4299 ).

The mean endothelial cell loss at 6 weeks postoperative in Group I was 185 Cells/mm2 (95% confidence interval - 159 - 211) and in Group II was 230 Cells/mm2 (95% confidence interval - 210 - 250).There was no statistically significant difference of mean ECL between Group I and Group II at 6 week postoperative ( p - value 0.3216 ) .

The mean endothelial cell loss at 6 months postoperative in Group I was 169 Cells/mm2 (95% confidence interval - 144 - 194) and in Group II was 202 Cells/mm2 (95% confidence interval - 175 - 229).There was no statistically significant difference of mean ECL between Group I and Group II at 6 months postoperative ( p - value 0.5928)

DISCUSSION:

Phacoemulsification has been shown to be safe for corneal endothelium. 7, 8, 9 However, postoperative visual acuity and complication rates are the same for phacoemulsification and SICS. 7, 10, 11

There is a wide variation in endothelial cell loss between the various studies even when the mode of surgery is same (e.g. SICS). This is due to various factors including, different inclusion and exclusion criteria, different grades of cataract, different methods of nucleus delivery in SICS, different types of irrigating solution and viscoelastics. 12 The reported endothelial cell loss remains unknown. 13, 14 Endothelial cell losses begin soon after surgery, continue for at least 10 years postoperatively and may persist throughout the patients life.

A study reported a 10% reduction in endothelial cells in both groups. Another study found that ECC decreased by 4.27%, 4.21% and 5.41% respectivley in ECCE, MSICS and phacoemulsification groups with no significant difference between the three groups. 15, 16, 17, 18

Another study found that mean cell loss was 11.8% in the phacoemulsification group, 12.8% in ECCE group that underwent CCC and 10.1% in the ECCE group underwent letterbox capsulotomy. The occurrence of posterior capsular rupture and vitreous loss at surgery leads to a statistically signficant higher endotherlial cell loss (18.9% vs. 11.5%; p = 0.003). 19, 20 However this factor did not affect the results of the current study as we excluded all cases with capsular rupture.

In the present study, over 6 months, there was decrease in cell density of 169 cell/mm2 for phacoemulsification and 202 cell/mm2 for MSICS. 21 Various modifications of SICS (irrigating vectis, viscoexpresion of the nucleus, anterior chamber maintainer, high density viscoelastics) have significantly reduced the endothelial cell loss.

Indian study has shown that safety to the endothelium was similar with the use of sodium hyaluronate for phacoemulsification and HPMC for MSICS. 22, 23 Another study from Italy has shown no siginficant decrease in mean endothelial cell density with the use of four different viscoelastics (HPMC, Healon, Healon GV and Viscot). Hence we opted for HPMC in MSICS.

A study from Italy compared endothelial cell damage between sclera tunnel incisions and clear corneal tunnel. Contrary to our study, concluded that sclera tunnels led to less postoperative endothelial cell damage than clear corneal tunnels. Because MSICS was performed through the sclera tunnel incision, it may have caused less endothelial cell loss than phacoemulsification performed through a clear corneal tunnel incision.

Short term follow up may give loss of density of endothelial cells more compared to long term follow up. In the present study it is the limitation. The follow up period was only 6 months after operation.

Dick B, Kohnen et al assessed the relationship between corneal endothelial cell loss after phacoemulsification and the location of the clear corneal incision.7 The study concluded that supero-temporal phacoemulsification incision may entail less ECL as compared to other incisions (although not significantly different). The amount of central ECL may be less marked in patients with longer axial lengths and with procedures utilizing fewer EFTS.

Ravalico G, Tongnetto D, et al compared the corneal and foveal changes of Viscoat and Visthesia in patients undergoing uneventful phacoemulsification cataract surgery.5

This study suggests that Viscoat is more safe and protective for the corneal endothelium during uneventful phacoemulsification cataract surgery, while Visthesia is in superior position regarding intraoperative pain. Patients of both groups acquired excellent visual acuity postoperative. Finally, this is the first study comparing OVDs in terms of macular thickness, finding that Visthesia cause a greater increase in macular thickness prostoperatively then Viscoat, although it reaches normal ranges in both groups Diaz-Valle D, Benitez del Castillo Sanchez JM et al study evaluated intra-operative endothelial damage after planned extra capsular cataract extraction (ECCE) with difference capsulotomy techniques and phacoemulsification.

The study concluded that endothelial response was not statistically significantly different among the surgical techniques, although endothelial damage was lower in Group 3, which could indicate a protective effect of the anterior capsule during cataract extraction. Endothelial barrier function remained disturbed despite the apparent morphological stabilization.

Beltrame G, Salvetat ML compared endothelial damage induced by different cataract incision sites and sized using specular microscopy.6

The study concluded that sclera tunnel group had less postoperative endothelial damage than the 2 CCI groups, with a statistically significant difference at the 12 o’clock position. This is probably because the sclera tunnel incision is placed more posteriorly and therefore induces less direct and indirect endothelial trauma

George R et al To investigate whether modern phacoemulsification surgery results is more damage to the corneal endothelium than extra capsular cataract extraction (ECCE) and to examine which preoperative, operative, and postoperative factory influence the effect of cataract surgery on the endothelium.2 The study concluded that there is no significant difference in overall corneal endothelial cell loss was found between these 2 operative techniques. The increased risk of severe cell loss with phacoemulsification in patients with hard cataracts suggests that phacoemulsification may not be the optimal procedure in these cases, and that ECCE should be preferred.

George R et al2 study compared the morphological (cell density, coefficient of variation and standard deviation) and functional (central corneal thickness) endothelial changes after phacoemulsification versus manual small-incision cataract surgery (MSICS).

The study concluded that central corneal thickness, coefficient of variation, and standard deviation were maintained in both groups indicating that the function and morphology of endothelial cells was not affected despite an initial reduction in endothelial cell number in MSICS. Thus, MSICS remains a safe option in the developing world.  

CONCLUSION:

The key factor of ECL in cataract surgery is surgical manipulation in anterior chamber and extraction of nucleus. In phacoemulsification group, the maneuvering was performed in the capsular bag and newer advanced phacoemulsification units with better fluidics reduced the chances of endothelial damage. In MSICS group, Viscoexpression of the nucleus significantly reduced the endothelial cell loss. To conclude there was no difference in safety between MSICS and phacoemulsification

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