TNOA Journal of Ophthalmic Science and Research

ORIGINAL ARTICLE
Year
: 2021  |  Volume : 59  |  Issue : 4  |  Page : 364--367

A study on measurement of central corneal thickness changes in postoperative period of phacoemulsification cataract surgery


Varshav Gore, Mamta Ramesh Agrawal, Ayushi Choudhary, Jesmin Alex, Abha Shah 
 Department of Ophthalmology, MGM Medical College, Navi Mumbai, Maharashtra, India

Correspondence Address:
Dr. Mamta Ramesh Agrawal
Alaknanda Building, D-3/304, Lokgram Netivali Road, Kalyan East, Thane, Maharashtra
India

Abstract

Purpose: Phacoemulsification has gained its importance with time due to its various benefits; however, it has one worrisome side effect which results due to endothelial pump failure, following surgery being corneal edema. This manifests as changes in central corneal thickness (CCT) which may further lead to falsely elevated intraoperative pressure (IOP) and ultimately hampering the vision; hence, the purpose of the study was conducted to find out the changes in CCT value following surgery. Materials and Methods: Randomly, 50 patients were considered for the study. It was a prospective hospital-based study, wherein patients were evaluated over a period of 1 month. Patients with right eye cataract considered as the case and left eye serving as the control were taken for the study. CCT measurements were recorded using pachymeter preoperatively, 1 h postoperatively, and on day 1, day 7, day 14, day 21, and day 30 postoperatively, and the findings were recorded. Surgical Procedure: Patients with right eye cataract grading of 2–3 nuclear sclerosis were taken for phacoemulsification cataract surgery. Before taking for the surgery, the preoperative CCT measurements using pachymeter were taken in all the quadrants and noted. Phacoemulsification was performed using the bevel-down phaco tip. Machine used was Oertli phacoemulsification catarhex. Sodium hyaluronate 1.4% was used as the viscoelastic substance. Phacoemulsification of the nucleus was performed with the help of phaco chop technique, with a 0° 20-gauge phaco tip. The nucleus was stabilized with phacoemulsification tip bevel down. The nucleus was broken down into several pieces and was aspirated and irrigated. Incision was secured with stromal hydration and eye was patched. Postoperatively, patients were advised to put topical antibiotic and steroids. After an uneventful phacoemulsification surgery, CCT was measured by the same surgeon immediately 1 h postoperatively, and patients were followed up on postoperative day 1, day 7, day 14, day 21, and day 30. Results: The CCT measured with the mean value of 606.04 ± 6 μm in postoperative day 1; on day 14, the CCT mean value was 553.81 ± 4 μm, and over a period of 1 month, the CCT value mean value was 544 ± 2 μm. It can be observed that the CCT measurement gradually decreases with time and returns to near-normal state on day 30. Conclusion: In our study, it was noted that the CCT value decreases gradually and returns back to near-normal value on day 30.



How to cite this article:
Gore V, Agrawal MR, Choudhary A, Alex J, Shah A. A study on measurement of central corneal thickness changes in postoperative period of phacoemulsification cataract surgery.TNOA J Ophthalmic Sci Res 2021;59:364-367


How to cite this URL:
Gore V, Agrawal MR, Choudhary A, Alex J, Shah A. A study on measurement of central corneal thickness changes in postoperative period of phacoemulsification cataract surgery. TNOA J Ophthalmic Sci Res [serial online] 2021 [cited 2022 Nov 29 ];59:364-367
Available from: https://www.tnoajosr.com/text.asp?2021/59/4/364/333153


Full Text



 Introduction



Cataract is one of the major causes of visual impairment and the leading cause of blindness in the world. There are 39 million people reported to be blind worldwide.[1] Phacoemulsification is one of the most common treatment modalities for cataract surgery. It has gained its importance due to its smaller incision, shorter recovery time, low induced astigmatism, rapid visual rehabilitation, and lesser incidence of surgical complications as compared to the conventional surgeries. Use of topical anesthesia in the surgery also reduces the local anesthetic agent and injection-related complications. Furthermore, the demand for phacoemulsification has increased due to premium intraocular lenses (IOL) such as toric and multifocal IOL, as they provide good vision at a larger range of distances than standard IOL. However, it has been observed that there occur different anterior segment changes after phacoemulsification cataract surgery out of which corneal endothelium is the most adversely affected structure.

Several studies have stated that corneal endothelial cell loss is caused by irrigation flow, turbulence of fluid, formation of cavitation bubbles, and direct trauma caused by the heat which is generated by phacoemulsification devices, which reduces corneal metabolism postoperatively.[2] The extent of postoperative endothelial cell loss depends on intraoperative phacoemulsification time. In addition, shorter eyes have a significantly higher incidence of endothelial cell loss, probably because of a more shallow anterior segment. Measuring corneal thickness changes after phacoemulsification has been used to assess surgically induced corneal edema.[3] It has been observed that the degree of permanent corneal endothelial damage is related to the degree of early postoperative corneal swelling. In addition, bevel-up phacoemulsification tip which directs the phacoemulsification energy toward the cornea causes corneal endothelial loss.[4]

Therefore, because of endothelial pump failure, corneal edema occurs which manifests as increase in central corneal thickness (CCT) value and thereby falsely elevating the intraocular pressure (IOP). Corneal edema remains one of the main factors hindering the postoperative visual rehabilitation after cataract surgery.

Thus, measuring the differences in pachymetry preoperatively and postoperatively seems useful in assessing the effects of phacoemulsification on corneal integrity.[5]

Aim

To study the measurement of CCT changes in thecpostoperative period of phacoemulsification cataract surgery.

Objectives

To compare the preoperative CCT with postoperative CCT values at 1 h and on day 1, day 7, day 14, day 21, and day 30 and to find out when it returns to near-normal value.

Eligibility criteria

Patients with senile immature cataract were included in the study.

Inclusion criteria

Age above 50 yearsRight eye cataract grading of 2–3 nuclear sclerosisWillingness to undergo pachymetry to measure CCT changes after phacoemulsification cataract surgeryAble to follow study instructionsPatients with reduced visual acuity due to cataract.

Exclusion criteria

Any corneal pathologies such as trauma and keratoconus.

Study period

March 1, 2021, to April 1, 2021

Type of the study

Prospective study.

Sample size calculation

Nonprobability (convenient sampling method).

Source of data

Patients with right eye senile cataract who came to the department of ophthalmology and were assigned to undergo phacoemulsification surgery in a tertiary care hospital were taken.

Statistical analysis

Statistical analysis was done using IBM Corp. Released 2012. IBM windows version 21.0. Armonk, NY.

Study procedure

Randomly, 50 patients were considered for the study with 28 males and 22 females [Figure 1] with right eye cataract and left eye serving as the control, preoperative and postoperative CCT measurements were evaluated for 30 days.{Figure 1}

All the statistical analysis was done using the software SPSS version 20.0.

The study was carried out after taking well informed consent and after obtaining ethical committee clearance.

Methodology

Data were collected after informed consent. Initial evaluation of vision, anterior segment, cataract grading, and fundus were recorded. CCT was measured preoperatively and postoperatively. Topical eye drop paracaine was instilled in both eyes. Patient was made to look straight in primary gaze. Patient was advised not to move the fixation gaze. With all sterile technique, CCT was measured with the help of ultrasonic pachymeter probe (Pachette 4) [Figure 2] in four different quadrants and at center and the average values were calculated and the findings were recorded for each eye [Figure 3]. After measuring the readings, topical antibiotic drops were instilled in both eyes.{Figure 2}{Figure 3}

 Results



A sample size of 50 patients was examined in the study, out of which 22% were males, 28% were females. For each patient, the right eye was the operated eye and left eye served as a control.

[Table 1] shows that the mean value between the operated eye and the control eye in immediate 1 h postoperative period is 606.04 ± 6 μm in the right eye followed by a gradual decline with the resolution of edema. On day 1 postoperatively, the CCT mean value was 606.04 ± 6 μm, and on day 14 postoperatively, the values was 553.81 ± 4 μm. However, the CCT values were observed to return to near normal state over a period of 1 month which was 544 ± 2 μm. [Graph 1] shows a spike in CCT in immediate postoperative period and gradually return to near-normal value whereas the left eye serving as the control eye showed no significant difference in CCT values over the whole examination period.{Table 1}[INLINE:1]

Therefore, in our study, as shown in [Graph 2], we conclude that there is statistically significant difference between preoperative value, immediate postoperative value, and CCT value on day 1, day 7, and day 30 between cases and controls.[INLINE:2]

 Discussion



Various researchers have found different anterior segment changes after phacoemulsification cataract surgery, out of which the cornea is most commonly affected, and CCT changes after phacoemulsification cataract surgery which appears due to corneal edema, which gradually settles over a period of time. Surgical techniques may influence the barrier function of the endothelium due to endothelial cell loss[6] The transient postoperative corneal swelling that commonly occurs after phacoemulsification is probably the result of damage to endothelial cells by the surgery.[7] Many factors can cause endothelial injury during cataract surgery, such as direct mechanical trauma, ultrasound energy, and the irrigating solution. Endothelial cells are nonreplicative, and consequently, the damaged area is covered by enlargement and migration of residual cells.[8] Increased CCT values falsely increase IOP value as well. Therefore, care has to be taken while taking these falsely elevated values, and corrected IOP values should be estimated and determined. Corneal edema also affects the vision, and thus, postoperative counseling of the patient about the visual outcome is dependent on the edema, which is estimated using CCT.

Swapnagandha et al. conducted a study and stated that the mean CCT increases after uneventful phacoemulsification cataract surgery and returned to normal values at 1 month postoperative period. As per the study, the CCT increased to 605.0 ± 8 μm on postoperative day 1, our study showed CCT value increased to 606.04 ± 6 μm on postoperative day 1, then it changed to 570.0 ± 4 μm on postoperative day 14, whereas our study showed CCT value to be 553.81 ± 3 μm which decreased to 550.3 ± 4 μm on postoperative day 30; our study showed CCT value to be 544 ± 2 μm. Increased CCT after cataract surgery appears to be due to corneal edema, which gradually settles over next 1–4 weeks.[9]

As compared to preoperative CCT values, the increase in CCT values on postoperative day 1 is the highest. The possible explanation for this may be the grade of cataract, duration of surgery, and type of machine used. This study provides valuable information regarding preoperative and postoperative rise in CCT which may further cause falsely elevated IOP reading which helps in determination of visual outcome after surgery which is affected due to corneal edema.

Hence, CCT values and IOP values should be monitored on regular intervals and noted. Corrected IOP is a reliable parameter to be measured. This was stated by Kolhaas et al. where the association between the CCT measurements and IOP values measured finding an approximately 1 mmHg correction for every 25 μm deviation from a CCT of 550 μm.[10]

As per Tranos et al., cataract surgery is associated with 25% transient elevation in IOP spikes after 4-6 hours of phacoemulsification cataract surgery.[11]

Tranos et al. recommended not treating postoperative IOP spikes in healthy eyes as there is no evidence suggesting that the transient IOP spikes produce significant damage or glaucomatous change.

 Conclusion



In our study, we found out that the CCT increased in the immediate postoperative period. It remained increased on day 1 compared with preoperative values and gradually reduced to near-normal levels over a period of 1 month.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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