Phacoemulsification causes increase in peripheral corneal thickness: A cross-sectional study

Ritesh Kumar Chaurasiya; Akansha Gupta; Sarbojeet Goswami

doi:10.4103/pajo.pajo_44_22

ORIGINAL ARTICLE

Year : 2022 | Volume : 4 | Issue : 1 | Page : 49

Phacoemulsification causes increase in peripheral corneal thickness: A cross-sectional study

Ritesh Kumar Chaurasiya¹, Akansha Gupta², Sarbojeet Goswami³
¹ Department of Optometry, Sanjivni Eye and Medicare Centre, Ambala, Haryana, India
² Department of Optometry, Dr. Om Parkash Eye Institute, Amritsar, Punjab, India
³ Department of Optometry, Arka Jain University, Jamshedpur, Jharkhand, India

Date of Submission	21-Aug-2022
Date of Decision	05-Sep-2022
Date of Acceptance	16-Sep-2022
Date of Web Publication	28-Oct-2022

Correspondence Address:
Ritesh Kumar Chaurasiya
Department of Optometry, Sanjivni Eye and Medicare Centre, Ambala - 134 003, Haryana
India

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/pajo.pajo_44_22

Abstract

Aim: The aim of the present study was to compare the central and peripheral corneal thickness before and after cataract surgery during three postoperative visits.
Materials and Methods: Prospective, comparative study was carried out among 92 patients who underwent cataract surgery in right eye. The central and peripheral corneal thickness (nasal, temporal, superior, and inferior) was measured using anterior segment optical coherence tomography before and after cataract surgery. The mean value of the corneal thickness was compared between preoperative and postoperative.
Results: The central corneal thickness (CCT) showed statistically significant differences between preoperative and postoperative measurement during all follow-up visits including 3 days. We also found statistically significant differences at all locations during a postoperative visit at 3 days. Superior, nasal, and inferior points on cornea were found to have significant differences when measured preoperatively and postoperatively at 1 month. A positive correlation was established between cataract grade and CCT during a postoperative 3-day visit using Pearson's correlation.
Conclusion: CCT was found to increase significantly after cataract surgery. There was a significant increase in peripheral corneal thickness right after cataract surgery.

Keywords: Cataract surgery, peripheral, central, thickness, phacoemulsification

How to cite this article:
Chaurasiya RK, Gupta A, Goswami S. Phacoemulsification causes increase in peripheral corneal thickness: A cross-sectional study. Pan Am J Ophthalmol 2022;4:49

How to cite this URL:
Chaurasiya RK, Gupta A, Goswami S. Phacoemulsification causes increase in peripheral corneal thickness: A cross-sectional study. Pan Am J Ophthalmol [serial online] 2022 [cited 2023 Mar 23];4:49. Available from: https://www.thepajo.org/text.asp?2022/4/1/49/359846

Introduction

Cataracts and refractive errors are the two leading causes of vision impairment and blindness.^[1] Age-related cataract is characterized by clouding of the normally transparent crystalline lens, resulting in partial to complete visual loss.^[2] The total number of cataract blinds increased to 8.25 million by the year 2020.^[3] The most common cataract procedure is phacoemulsification cataract surgery with the implantation of a posterior chamber (behind the iris), intraocular lens within the capsular bag.^[4] It had also been observed that damage of the corneal endothelium cells during cataract surgery may lead to a transient increase in corneal thickness.^[5] Some authors have reported that all patients regained preoperative values after 4 weeks,^[6],[7] whereas others have found increases to be sustained up to 3 months postoperatively.^[8] Bolz et al.^[9] found nasal–temporal difference in corneal thickness preoperatively in all patients. In addition, there was prolonged corneal thickening at 3.0 mm eccentricity after cataract surgery. Central corneal thickness (CCT) is known to affect the accuracy and reliability of intraocular pressure (IOP) measurements by applanation tonometry.^[10] There has been increased attention regarding the measurement of CCT during the management of glaucoma since it influences the intraocular pressure when measured with Goldmann Applanation Tonometer. Several literatures have demonstrated a positive correlation between CCT and IOP measured by applanation which causes overestimation of true IOP in thicker corneas and the converse in thinner ones.^[11] Several studies conducted in the past explain changes in CCT after surgery.^{[5],[6],[7],[8],[9]}

Taking all facts into consideration, this study aimed to compare the differences in corneal thickness along four peripheral positions on cornea along the limbal region before and after cataract surgery.

Materials and Methods

This prospective, comparative study was conducted at tertiary eye care hospital in the northern region of India. Convenient sampling was used for the inclusion of patients for this study. All the patients who attended the hospital for cataract surgery in right eye were invited to participate in the study. All the patients between the ages of 50 and 65 years with a senile cataract were included in the study, whereas patients having any corneal degeneration, corneal opacity, diabetes mellitus, pseudoexfoliation syndrome, traumatic cataract, glaucoma, complicated cataract, or having a history of any previous ocular surgeries were excluded from the study. All the participants were given informed consent along with the purpose of the study and the study also adhered to the tenets of the Declaration of Helsinki.

Surgical technique

Phacoemulsification is a modern-day cataract surgery that employs ultrasound energy to emulsify the nucleus, vacuum to catch the nuclear material, and irrigation and aspiration for cortex and viscoelastic removal. A typical phaco machine consists of a handpiece, foot pedal, irrigation, and aspiration system. During surgery for this study, a side-port incision was made on the superior side in the right eye. The anterior capsule was visualized using trypan blue staining. After washing out excess trypan blue with irrigation and aspiration, the anterior chamber was filled with an ophthalmic viscosurgical device (2.0% Hydroxypropyl Methyl Cellulose, Appasamy Associates^®). The anterior capsule was then opened by continuous curvilinear capsulorhexis using forceps, and hydrodissection was performed meticulously to avoid capsular block syndrome. Similarly, the solution used during phacoemulsification was Clearsol (Appasamy Associates, Chennai, India).

Clinical examination

Ophthalmic assessment included visual acuity assessment, slit lamp examination, IOP measurement, refraction, and corneal curvature. IOP was measured using a noncontact air-puff tonometer (Topcon CT-80; Topcon Corp., Tokyo, Japan). Refraction and corneal curvature were measured using an autorefractor (Topcon KR-8800; Topcon Corp.). The corneal thickness along five points was measured preoperatively and postoperatively using anterior segment optical coherence tomography (AS-OCT) (Nidek RS-3000 Advance 2; Nidek Co. Ltd, Japan) [Figure 1]. For each patient, the corneal thickness was measured at the following follow-up visits: preoperative, 3 days postoperative, 1 month postoperative, and 2 months postoperative. All measurements were performed by a single examiner during every visit. The mean of three readings for each parameter was used for further analysis.

Figure 1: Diagram showing five locations on cornea used for measuring corneal thickness before and after cataract surgery

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Statistical analysis

Statistical analysis was performed using SPSS software (IBM SPSS, version 25; IBM Corp., Armonk, NY, USA). Frequencies and percentages were described for categorical data such as gender. Mean and standard deviation were described for quantitative variables such as age and corneal thickness. Data normality was evaluated using Shapiro–Wilk test (P < 0.05). Paired t-test was used to compare the mean corneal thickness between four visits (preoperative, 3 days postoperative, 1 month postoperative, and 2 months postoperative). Pearson correlation test was conducted to evaluate the association between postoperative corneal thickness and cataract grade. Statistical Significance was considered if P > 0.05.

Results

Among 92 participants during the study period, 52 (56.52%) were male and 40 (43.48%) were female. The mean age of the patient was 55.26 years with a standard deviation of 3.320 years. Similarly, preoperatively 36 (39.13%) patients had cataracts of grade NS II, 40 (43.48%) had Grade III and 16 (17.39%) had cataract grade of NS IV according to Lens Opacification Classification System – III (LOCS – III) [Figure 2].

Figure 2: Bar graph showing number of patients with different cataract grade preoperatively

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The CCT measured with AS-OCT showed statistically significant differences between preoperative and postoperative measurement during all follow-up visits including 3 days (t = −10.170, P = <0.05), 1 month (t = −6.510, P = <0.05), and 2 months (t = −4.427, P = <0.05) [Table 1]. Similarly, comparing all the measurements at each peripheral point on cornea, we also found statistically significant differences at all locations during a postoperative visit at 3 days with P > 0.05. During the other two postoperative visits (1 and 2 months), superior, nasal, and inferior points on cornea were found to have statistically significant differences when measured preoperatively and postoperatively at 1 month, and none of the points during measurement of peripheral corneal thickness were found significant differences at 2 months of postoperative visit [Table 1].

Table 1: Comparison between mean corneal thickness before and after cataract surgery

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In addition, using Pearson correlation test, positive correlation was established between cataract grade and CCT during postoperative 3-day visit (r = 0.425, P = 0.043). Thickness at peripheral points were not statistically significant, however, there was positive association observed between cataract grading including superior corneal thickness at 3-day, 1-, and 2-month visit (r = 0.164, P = 0.45; r = 0.187, P = 0.39; r = 0.236, P = 0.27), respectively. Unlike superior corneal thickness, the other three point's thickness (nasal, inferior, and temporal) had a positive correlation during two visits only 3 days and 1 month). The correlation coefficient along with P value is represented in [Table 2].

Table 2: Correlation between cataract grading and corneal thickness

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Finally, post hoc test reveals that the corneal thickness depends on the cataract grading during the early visit after surgery (3 days) with P > 0.05 when compared with the later visit (1 and 2 months).

Discussion

The stromal layer of cornea has a tendency to swell under normal physiological conditions. This swelling is prevented by active fluid pumping of the endothelium, thereby assuring maintenance of normal thickness and transparency of the cornea.^[12] Phacoemulsification may influence the barrier function of the endothelium due to endothelial cell loss during surgery.^[13] The transient postoperative corneal swelling that commonly occurs after phacoemulsification is probably the result of damage to endothelial cells by the surgery.^[13] The present study aimed to evaluate and compare the central and peripheral corneal thickness before and after cataract surgery. We found an increase in CCT for more than 2 months after cataract surgery. However, the peripheral corneal thickness measured at different points increased for 1 month and decreased by 2 months postoperatively. Salvi et al.^[14] reported a 13.81% increase in CCT before and after 1 h of cataract surgery but thickness (0.54%) returned to preoperative value after 1 week of surgery. A similar finding was also noted in the present study where we found a 3.50% increase in CCT after 3 days of cataract surgery. We noticed that the CCT was decreasing after 1 month but the thickness did not returned to normal value after 2 months of cataract surgery in the present study. In a study by Falkenberg et al.,^[15] an average increase of 37 μm in CCT on the 1^st postoperative day, and returning to preoperative values within an average of 27 weeks were noted in past studies. This finding is similar to the present study where the increase of 18 μm in CCT was noted after 3 days of surgery. These differences of changes in CCT from Falkenberg et al. can be due to differences of postoperative measurement. In the present study, the peripheral corneal thickness showed an average increase of 7 μm after 3 days of cataract surgery that returned to a preoperative value within 2 months. Similarly, Aribaba et al.^[8] found an increase in mean baseline CCT from 520.6 ± 20.3 μm by 76.9 μm (597.9 ± 30.4 μm) 24 h after cataract surgery, followed by a relative reduction in the mean CCT to 555.2 ± 24.7 μm and 525.1 ± 19.7 μm at 2 weeks and 12 weeks, respectively. Bilak et al.^[16] reported that CCT increased significantly from 531.0 ± 38.99 μm before phacoemulsification to 533.72 ± 44.87 μm postoperatively. The present study has a slight contradiction with Aribaba et al. study as the present study showed a marked relative reduction of CCT in 2 months. The reduction time in our study was comparatively smaller than Aribaba et al. This may be due to the technique approached for cataract surgery. Takmaz et al.^[17] measured CCT at 545.7 ± 36.2 μm before cataract surgery and at 550.5 ± 40.2 μm in the 1^st postoperative month, although this increase was not statistically significant. In a similar study by Yağcı et al.,^[18] no significant difference was found between CCT values in the 1^st postoperative month and preoperative measurements. Similarly, Abbas et al.^[19] also found no significant differences between preoperative and postoperative measurements after 1 month of cataract surgery. In the present study, we found statistically significant differences between CCT variation during all postoperative visits while peripheral corneal thickness was significant after3 days of cataract surgery, followed by nonsignificant relationships during 1 and 2 months postoperative visits. Finally, the present study could not be compared to Olsen and Eriksen study^[20] and Kohlhaas et al. study^[21] where preoperative corneal thickness values were reached by 6 and 12 months, respectively, as our study patients were only followed up for 2 months.

The findings of the present study can be interpreted with few limitations. First, the data were collected up to 2 months after cataract surgery, and second, a single surgeon was involved in cataract surgery. Future studies can be done in a similar manner where the postoperative corneal thickness can be measured for a longer period of time. Similarly, future studies can also be done by taking incision location, cataract grade, and corneal thickness into consideration along with endothelium cell density to assess the postoperative corneal profile after cataract surgery.

Conclusion

We found a significant increase in central and peripheral corneal thickness right after cataract surgery. The peripheral thickness, however, came to preoperative reading within 2 months of cataract surgery. Similarly, the density of cataracts was directly proportional to an increase in central and peripheral corneal thickness. The study concluded that phacoemulsification causes corneal thickness to increase over a certain period of time.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

References

1.	World Health Organization; Blindness and Visual Impairment; Available from: https://www.who.int/news-room/fact-sheets/detail/blindness-and-visual-impairment [Last accessed on 2022 May 29].
2.	Nizami AA, Gulani AC. Cataract. In: StatPearls. Treasure Island (FL): StatPearls Publishing; 2021.
3.	Murthy G, Gupta SK, John N, Vashist P. Current status of cataract blindness and vision 2020: The right to sight initiative in India. Indian J Ophthalmol 2008;56:489-94. [PUBMED] [Full text]
4.	Trivedi RH, Werner L, Apple DJ, Pandey SK, Izak AM. Post cataract-intraocular lens (IOL) surgery opacification. Eye (Lond) 2002;16:217-41.
5.	Bamdad S, Bolkheir A, Sedaghat MR, Motamed M. Changes in corneal thickness and corneal endothelial cell density after phacoemulsification cataract surgery: A double-blind randomized trial. Electron Physician 2018;10:6616-23.
6.	Cheng H, Bates AK, Wood L, McPherson K. Positive correlation of corneal thickness and endothelial cell loss. Serial measurements after cataract surgery. Arch Ophthalmol 1988;106:920-2.
7.	Abdelhalem R, Saif MY, Mohamed S. Central corneal thickness before and after phacoemulsification in non-diabetic and diabetic patients without retinopathy. NILES J Geriatr Gerontol 2020;3:15-22.
8.	Aribaba OT, Adenekan OA, Onakoya AO, Rotimi-Samuel A, Olatosi JO, Musa KO, et al. Central corneal thickness changes following manual small incision cataract surgery. Clin Ophthalmol 2015;9:151-5.
9.	Bolz M, Sacu S, Drexler W, Findl O. Local corneal thickness changes after small-incision cataract surgery. J Cataract Refract Surg 2006;32:1667-71.
10.	Damji KF, Muni RH, Munger RM. Influence of corneal variables on accuracy of intraocular pressure measurement. J Glaucoma 2003;12:69-80.
11.	Ko YC, Liu CJ, Hsu WM. Varying effects of corneal thickness on intraocular pressure measurements with different tonometers. Eye (Lond) 2005;19:327-32.
12.	Mishima S. Clinical investigations on the corneal endothelium-XXXVIII Edward Jackson memorial lecture. Am J Ophthalmol 1982;93:1-29.
13.	Behndig A, Lundberg B. Transient corneal EDEMA after phacoemulsification: Comparison of 3 viscoelastic regimens. J Cataract Refract Surg 2002;28:1551-6.
14.	Salvi SM, Soong TK, Kumar BV, Hawksworth NR. Central corneal thickness changes after phacoemulsification cataract surgery. J Cataract Refract Surg 2007;33:1426-8.
15.	Falkenberg B, Kutschan A, Wiegand W. Analysis of optical parameters after cataract surgery and implantation of foldable lens. Ophthalmologe 2005;102:587-91.
16.	Bilak S, Simsek A, Capkin M, Guler M, Bilgin B. Biometric and intraocular pressure change after cataract surgery. Optom Vis Sci 2015;92:464-70.
17.	Takmaz T, Kösekahya P, Kürkçüoğlu PZ. Anterior segment morphometry and intraocular pressure change after uneventful phacoemulsification. Turk J Med Sci 2013;43:289-93.
18.	Yağcı R, Güler E, Uzun F, Gürağaç BF, Acer S, Hepşen İF. Assessment of anterior chamber parameters after cataract surgery by galilei dual scheimpflug analyzer. Eye Contact Lens 2015;41:40-3.
19.	Abbas H, Rauf A, Perveen S, Mehmood SH, Hussain I, Naimat K et al. The association of cataract type on central corneal thickness after phacoemulsification cataract surgery. PAFMJ 2021;71:1611-4.
20.	Olsen T, Eriksen JS. Corneal thickness and endothelial damage after intraocular lens implantation. Acta Ophthalmol (Copenh) 1980;58:773-86.
21.	Kohlhaas M, Stahlhut O, Tholuck J, Richard G. Changes in corneal thickness and endothelial cell density after cataract extraction using phacoemulsification. Ophthalmologe 1997;94:515-8.