Refraction and Intraocular Pressure Changes After YAG Laser Posterior Capsulotomy in Posterior Capsular Opacification

INTRODUCTION

The Most common cause of blindness and vision diminution in the world is Cataract with its all-different types, Cataract treatment was only surgical. Cataract surgery developed over years and nowadays the most common types are Phacoemulsification and extracapsular cataract extraction (ECCE).¹

It is common for patients to develop Posterior Capsular Opacification within months or years after undergoing a routine cataract extraction procedure. PCO may cause visual impairments such as foggy or hazy vision, poor contrast sensitivity, halos around lights, and difficulty in reading. ¹

This condition is known medically as "secondary cataract", which is formed by the remaining sub-capsular epithelial lens cells that migrate, proliferate and differentiate leading to opacity, decreased visual acuity and other visual disturbances as blurring of vision especially when involving visual axis ¹

PCO incidence is between 20% and 50% of patients who have a routine cataract extraction procedure. There is no substantial data to support claims that PCO prevalence has decreased in recent years ² PCO is more prevalent in newborns and babies, and if it develops

.early, it may result in amblyopia. ^{3, 4, 5} Some reports stated that PCO is almost universal in children. ^{4, 6}

In PCO vision is reduced as a result of LECs accumulation and of pacification the intact posterior lens capsule. This results in light dispersion reducing visual acuity.¹

other factors affecting PCO incidence may include cytokines and growth factors, like transforming growth factor β, fibroblast growth factor 2 (FGF-2), and hepatocyte growth factor (HFG), as well as matrix metalloproteinases (MMOs). Exogenous hyaluronic acid (HA), which is an ingredient of numerous visco-elastic polymers used in the surgery, may enhance the incidence of PCO. ⁷

PCO has been treated by YAG laser capsulotomy; a procedure that creates an opening in the posterior capsule.⁹ Dr. Aron-Rosa was able to operate it at a range of wavelengths. In October 1978, she began conducting clinical trials. Over the following several years, 5000 eyes were cured.¹⁰ In November 1980, Fankhauser did his first YAG Session.¹¹

Previously, PCO was treated surgically, but now YAG Laser is the preferred therapy since it is non-invasive, quick, and successful; nevertheless, many developing countries do not have access to this treatment. Only a few potential adverse effects including IOL pitting, retinal detachment, IOP rise, corneal odema, IOL subluxation, iritis, macular hole, and the loss of corneal endothelial cells. ⁴

 Visual Symptoms is the main indication for YAG including increased glare, interfering with daily activities of patient, the other indication is to improve fundus viewing.

PATIENTS AND METHODS

Prospective interventional study included 50 eyes [17 eyes of males (33.3%), 33 eyes of females (66.7%)] with an average age from 22 to 70 [mean age 48.28±15.39] with posterior capsule opacification. Medical committee of ethics of Al-Azhar University, faculty of medicine approved the study. Informed consent was obtained from all participants included in the study after the nature and possible complication of the procedure was explained.

Inclusion criteria:

The patients with posterior capsule opacification after uncomplicated cataract surgery depend on their severity of PCO if mild or moderate.

Exclusion criteria:

Start with Patients less than 18 years old or who refused to participate in the study, patient with complicated cataract surgery or any ocular disease that may affect the study, very dense PCO or pregnant patients.

Preoperative Evaluation:

History taking and Preoperative ophthalmological examination:

Snellen's chart and the Landot C optotype (which was subsequently translated to the logarithm of the minimum angle of resolution (log MAR) scale) were used to compute the UCVA and BCVA, respectively, followed by Slit lamp Examination to assess Cornea, AC, Pupil reaction, IOL and Fundus using non-contact Volk 90 Diopter lens and diagnosis of PCO and grading.

Refraction using automated refractometer (KR-800; Topcon Corporation, Tokyo, Japan), Intraocular pressure (IOP) by Goldman Applanation tonometer (CT-80 Topcon Corporation) and Sirius- Shine-Flag Cam.

Operative steps and technique:

After explain the Procedure, Inform the patient about the procedure's aims, length, level of pain, and requirement for a solid fixation. It may seem as a little clicking noise to his ears. Informed Consent: Should obtained prior to the procedure. Pupillary Dilation (Mydriasis) by used Tropicalamide (1% concentration) and phenylephrine hydrochloride (2.5%) gave total mydriasis alleviation and Topical anesthesia was by using Benoxinate hydrochloride 0.5% eye drops

Comfortable Sitting of Patient: Adjustable stool and chinrest should comfortably adjusted to relax the patient. Steady Fixation Obtained by head strap prevents the patient from pulling their head back during Session then changing the brightness of the lighted target as required.

Contact Lens: Abraham capsulotomy YAG laser lens with lubricating gel (methylcellulose) used during the capsulotomy.

Room Illumination: By darkening or semi-darkening the laser chamber, surgeons may more precisely focus the laser beam on their target.

Slit-lamp Beam: It should be thin in form and have an acute angle. This provides information on the pupil's size under ambient light. Prior to a laser session, it is critical to adjust the slit-oculars. lamp's The slit light and aiming beams were moved to become Para focused for optimal performance.

Capsulotomy Technique:

We use an average 3.5±0.5 mJ / pulse from Q-LAS Nd: YAG laser, which was enough to open posterior capsule.

In intractable thick posterior capsules, the energy setting per pulse may be increased.

Begin with low energy and progressively increase as needed. Use the least amount of energy every pulse to make an opening in the posterior capsule.

In this study the average total laser shots was 35-60 with mean 48.09 and ±SD 9.18 among YAG session which was sufficient to create an adequate and optimum opening in the posterior capsule

The size of the capsulotomy is dictated by the pupil size under ambient light settings (approx.4-5 mm).

All Shots completed in one session for the patient.

Postoperative Management

All patients were given topical non-steroidal anti-inflammatory eye drops four times / day and Brimonidine tartrate 0.2% for one week following session (post Laser therapy).

Follow-Up Schedule

The postoperative visit scheduled within first week then after Month to do an ophthalmic examination of the Patients including BCVA, Slit lamp check, IOP measurements, Refraction measurements and corneal topography Sirius CSO (after 1 month).

Statistical analysis:

The recorded data evaluated using the statistical software for social sciences, version 23.0. (SPSS Inc., Chicago, Illinois, USA). In terms of numbers, we had medians, interquartile ranges, and the like.

The following tests were done:

For non-parametric data, use the Wilcoxon Signed-Rank Sum test to compare differences across time.

The Kruskal-Wallis test is used for multiple-group comparisons when analyzing non-parametric data.

Friedman The significance test was used for comparing similar samples.

For non-parametric two-group comparisons, the Mann Whitney U test was used.

One-way analysis of variance should be used to compare more than two means (ANOVA).

For numerous comparisons between variables, Tukey's test was used in the post-hoc test.

A 95 percent confidence range and a 5% acceptable error tolerance were used in this study. Because of this, the p-value considered significant:

Probability (P-value)

P-value < 0.05 considered significant.

P-value < 0.001 considered as highly significant.

P-value > 0.05 considered insignificant.

RESULTS

Tables showing the investigations and conclusions presented below. We studied the effect of YAG Capsulotomy in Pseudophakic eyes with PCO on Refraction, Astigmatism and Intraocular Pressure of Patient before and after treatment and we applied our study on 36 patients with the same inclusion and exclusion criteria.

Table 1: Baseline characteristics distribution among study group (n=50 eye)

Table 2: YAG session descriptive among study group.

The ranged shots number was 10–15 and mean was 12.56 and ±SD 1.85; while energy ranged 3.5-4 with mean 3.8 and SD 0.18, also ranged of total energy 35-60 with mean 48.09 and ±SD 9.18 among YAG session.

Values in each column which have different letters are significantly different at (P<0.05) using Friedman Test; p-value

Table 3: Comparison between pre session of UCVA “LogMar” and other measurements “After 1wk. and after 1months” among study group

We reported changes statically improvement of UCVA in follow up compared to pre session with p-value < 0.05; while there is ; while did not find statically different changes after 1wk. and after 1months with p-value (p>0.05).

Values in each column which have different letters are significantly different at (P<0.05) using Friedman Test; p-value

Table 4: Comparing between pre session of Auto-Refractometer “AR” SPH and other measurements “After 1wk. and after 1months” among study group

There was statistically significant improvement in follow up compared to pre session with p-value < 0.05; while we did not find significant changes statistically between after 1wk. and after 1months with p-value (p>0.05).

Values in each column which have different letters are significantly different at (P<0.05) using Friedman Test; p-value

Table 5: Compared between pre session of Auto-Refractometer “AR” Cylinder and other measurements “After 1wk. and after 1months” among study group

There was statistically significant improvement in follow up compared to pre session with p-value <0.05; while there is no significant difference between after 1wk. and after 1months with p-value (p>0.05).

Values in each column which have different letters are significantly different at (P<0.05) using Friedman Test; p-value

Table 6: Compare between pre session of Auto-Refractometer “AR” Axis and other measurements “After 1wk. and after 1months” among study group

There was statistically significant improvement in follow up compared to pre session with p-value <0.05; while there is no statistically between after 1wk. and after 1months with p-value (p>0.05).

Values in each column which have different letters are significantly different at (P<0.05) using Friedman Test; p-value

Table 7: Compare between pre session of Best corrected visual acuity “ BCVA” (LogMar) and other measurements “After 1wk. and after 1months” among study group

There was statistically significant improvement in follow up compared to pre session with p-value <0.001; while did not find different changes statically between after 1wk. and after 1months with p-value (p>0.05).

Values in each column which have different letters are significantly different at (P<0.05) using Friedman Test; p-value

Table 8: Compare between pre session of intraocular pressure (IOP) and other measurements “After 1wk. and after 1months” among study group.

There was statistically significant improvement in follow up compared to pre session with p-value < 0.05; while ; while did not find different changes statically between after 1wk. and after 1months with p-value (p>0.05).

Values in each column which have different letters are significantly different at (P<0.05) using Friedman Test; p-value

Table 9: Compare between pre session of Sirius CSO and after 1months among study group

According to Keratometer 1 readings, there is significant difference statistically with p-value between pre session and after 1 month (p<0.05).

Additionally there is significant difference statistically between pre session and after 1month according to Keratometer 2 reading with p-value (p<0.05).

Also, there significant difference statistically between pre session and after 1month according to average reading with p-value (p <0.05).

Values in each column which have different letters are significantly different at (P<0.05) using Friedman Test; p-value

Table 10: compared corneal astigmatism by Sirius CSO (cylinder) between pre session and after 1months among study group

We did not report different changes statically between pre session and after 1month according to cylinder with p-value (p>0.05).

Kruskal–Wallis was performed & Multiple comparison between groups through Mann-Whitney test

Values in each row which have different letters are significantly different at (P<0.05).

p-value >0.05 NS; *p-value

Table 11: Relation between posterior capsule opacity (PCO) grading according to delta change (pre-after 1m) of UCVA (LogMar), Auto-Refractometer, BCVA (LogMar), IOP, Corneal topography, Cylinder.

There was significant difference statistically between grades following delta change (pre-after1m) of UCVA “LogMar” with p-value (p<0.05). The highest value was found in grade I (-0.35±0.21) followed by grade II (-0.26±0.16) while the lowest value was found in grade III (-0.11±0.11).

Additionally, found significant difference statistically between grades following delta change (pre-after1m) of BCVA “LogMar” with p-value (p<0.05). The highest value was found in grade I (-0.26±0.08) followed by grade II (-0.19±0.06) while the lowest value was found in grade III (-0.12±0.08).

While, there was significant difference statistically between grades following delta change (pre-after1m) of IOP with p-value (p<0.05). The highest value was found in grade III (-0.80±1.69) followed by grade II (-1.00±1.77) while the lowest value was found in grade I (-1.38±2.06).

Also, reported significant difference statistically between grades following delta change (pre-after1m) of Axis with p-value (p<0.05). The highest value was found in grade I (-8.40±46.08) followed by grade II (-5.83±14.73) while the lowest value was found in grade III (-0.13±6.52).

There is no statistically significant difference between grades according to delta change (pre-after1m) of SPH, Cylinder, Axis, K1, K2, Average k, and Cylinder.