Harshal D Sahare^1*, Sujit M Murade², Kalyani D Narote³, Anamika H Agrawal⁴, Akshay M Jadhav⁵

^1,3Senior Resident, Department of Ophthalmology, K.B. Bhabha Hospital, Bandra, Mumbai, Maharashtra, INDIA.

²Associate Professor, Department of Ophthalmology, LTMMC and General Hospital, Mumbai, Maharashtra, INDIA.

⁴Additional Professor and HOU, Department of Ophthalmology, GSMC and KEM Hospital, Mumbai, Maharashtra, INDIA.

⁵Senior Resident, Department of Ophthalmology, Bhabha Hospital, Kurla, Mumbai, Maharashtra, INDIA.

Email: dr.harshalsahare@gmail.com, drsujitmurade@gmail.com, kalyaninarote52@gmail.com, dr.anamikaaha@gmail.com, akshayjadhav72@gmail.com

RESULTS

A total of 44 eyes of 44 patients who for cataract phacoemulsification surgery were included in this study. Mean age of the patient is 56.98 years with standard deviation of 05.98. There were 29 males and 15 females. Right eye surgery was done in 18 eyes and left eye surgery was done in 26 eyes. Refractive acceptance preoperatively was 0.50 D to 2.0 D.

Table 1: General characteristics

On slit lamp examination showed most common Cataract Nucleus grade is NS 3 with PSC preoperatively.

Table 2: Slit lamp examination showing Preoperative Lens changes.

Preoperatively mainly eyes had best visual activity between 6/24 to 6/18 while visual activity range from 6/60 to 6/12. Improved vision postoperatively day 90^th where vision was 6/6 unaided in 24 eyes out of 44 eyes and 6/9 in 14 eyes respectively.

Table 3: Best corrected visual acuity.

We observed improved diopteric difference by automated keratometry on postoperative 90^th day as compared to preoperative values.

Table 4: Change in Diopteric difference by Automated Keratometry.

Majority of patients had Preop Keratometric Difference (K1-K2) of 1.5 D, all required LRI Incisions length of 4 clock hours (60°).

Table 5: Comparisons of length of LRI according to Preop Keratometric Difference.

                  In 05 out of 10 patients above 50 years (50 %) got residual keratometric difference of 0.50D (emmetropic) as compared to 19 out of 34 (55.88%) patients below 50 years. So, from above we conclude that LRI is slightly more effective in patients above 50 years as compared to in patients below 50 years.

Table 6: Comparison of Effectiveness of LRI among Age groups.

In 08 out of 18 LE (44.44%) got residual keratometric difference of 0.50D (emmetropic) as compared to 16 out of 26 RE (61.53%) thus, LRI was more effective in LE as compared to RE.

Table 7: Comparison of Effectiveness of LRI between Eyes.

The mean dioptric power of the central cornea before surgery at presentation was +42.88920± 0. 886D. The mean dioptric power of the cornea at postoperative day 1 after surgery was 42.80114 ±0.646614D and at postoperative day 7 was 42.72727 ± 0.652741 D and at postoperative day 30 was 42.7216 ± 0.80913 and at postop day 90th was 42.71556 ± 0.54454 D. The mean astigmatic power of the central cornea before surgery was 1.707 ±0.5481 D. At postoperative day 1 after surgery, the mean astigmatic power of the cornea was 0.548 ± 0.810 D and 2.08 ± 0.609D at postoperative day 7 after surgery and at postoperative day 30 was 1.416 ± 0.0001D and 90^th day was 0.254 ± 0.210 D. There was decrease in corneal astigmatism after limbal relaxing incisions. The statistical analysis of the central corneal diopteric power using ANOVA (Analysis of Variance) was found to be statistically significant (p<0.001). Change in Refractive Index preop and postop is statistically significant (p-value <0.001).

Table 8: Mean diopteric power and astigmatic power of the cornea preoperatively and postoperatively according to Automated Keratometry.

Change in BCVA preop and postop is statistically significant (p-value <0.001). The mean preoperative best spectacle corrected Visual Acuity was 0.3 with a standard deviation of 0.1138 (in log MAR) and the best spectacle corrected visual acuity was 0.207 with a standard deviation of 0.258 on the postoperative day 1 and 0.177 with a standard deviation 0.001 at 1 week whereas the Best Spectacle Corrected Visual Acuity was 0.099 with a standard deviation of 0.6049 at postop day 30, mean BCVA 0.0544 with standard deviation 0.0252 on postop day 90^th. The difference between the visual acuity preoperatively and post operatively was found to be statistically significant with a p<0.01 by employing the statistical test Analysis of Variance (ANOVA). Visual outcome a change after limb relaxing incisions statistically significant. Keratometry changes preop and postop is statistically significant with p value <0.001

Table 9: Visual acuity Preop, day 1, day 7, day 30 and day 90 postop.

DISCUSSION

Preexisting corneal astigmatism at the time of cataract surgery can be treated by manipulation of cataract incision, limbal relaxing incisions (LRIs), astigmatic keratotomy, paired opposite clear corneal incision, implantation of toric intraocular lens, photorefractive keratotomy (PRK), laser in situ keratomileusis (LASIK) and recently penetrating limbal relaxing incisions (PLRIs).⁵ There are several approaches for reducing preexisting astigmatism during cataract surgery; perhaps the most basic is placement of incision along the steep corneal meridian taking the advantage of wound induced flattening. There are two major limitations of this approach. First with small incisions the with the rule flattening is insufficient to correct existing astigmatism in excess of approximately 2.00 D. Second, centering the incision on certain meridians is techniqually difficult (e.g. superonasal or inferotemporal in left eye. Limbal Relaxing Incisions are an effective way to reduce astigmatism at the time of cataract surgery. No adjustment to the surgeon’s preferred position of the cataract incision is needed with LRIs. Due to their placement at the outermost periphery of the cornea and their similarity to conventional cataract incisions, these incisions are simple to perform and unlikely to cause complications. The forgiving nature of the procedure represents another advantage.⁶ Disadvantages of the LRI includes requiring special instrumentation (diamond knife, or preset depth guarded disposable blades), possible weakening of the integrity of the globe and moderate variability in accuracy, presumably resulting from variations in individual wound healing pattern. LRIs can correct astigmatism up to 2D. LRIs also leave the central cornea untouched for other corneal refractive interventions for residual ametropia.⁷ To our advantage these LRIs did not lead to corneal haze that interfered with phaco surgery as the incisions were placed in the most peripheral cornea as reported by other studies. Advances in cataract and refractive surgery techniques, nomograms and intraocular lens (IOL) technology allow greater control over the patient’s postoperative refractive outcome and visual resolution. A surgeon may become more comfortable with one particular technique as compared to another and should, therefore, choose an approach which works best in his or her hands. In our study, in the LRI group we found that the mean preoperative astigmatism at postoperative day 1 after surgery, the mean astigmatic power of the cornea was 0.948±0.810D and 0.508±0.509D at postoperative day 7 after surgery and at postoperative day 30 was 0.416±0.406D and day 90^th was 0.254 ± 0.210 D respectively. There was decrease in corneal astigmatism after limbal relaxing incisions. Visual outcome a change after limb relaxing incisions statistically significant. Corneal astigmatism improved and 24 eyes were emmetropic (0.50 DC) on postop day 90^th with remaining residual cylindrical power ranges between 0.75 DC to 1.25 DC respectively. On postoperative day 44 all eyes were emmetropic with refractive power of 1.416 In a study titled Refractive outcomes after limbal relaxing incisions or femtosecond laser arcuate keratotomy to manage corneal astigmatism at the time of cataract surgery. The mean target induced astigmatism was 1.50 D and 1.38 D respectively, with 1.02 D and 1.23 D surgically induced astigmatism (P = .21), resulting in the femtosecond arcuate keratotomy group having a smaller difference vector (1.17 D versus 0.89 D; P = .02) and a greater correction index (0.48 versus 0.73; P = .02). Forty-four percent of patients in the femtosecond arcuate keratotomy group and 20% in the LRI group attained a postoperative cylinder of less than 0.50 D (P = .01). These results were statistically significant. The femtosecond arcuate keratotomy group achieved a higher correction index and a smaller difference vector. The femtosecond arcuate keratotomy patients showed less postoperative cylinder than LRI patients.⁸ The visual and refractive data are reported. UDVA and CDVA improved statistically (P<0.01). CYL value decreased by 78.1%. Analysis of KP90 and KP135 polar values show a statistical difference. (P=0.22 and P=0.24, Wilcoxon rank-sum test).⁷ Three years after procedure, it can be assumed that if an incisional procedure, such as LRIs, is added during phacoemulsification surgery, third-order aberrations in cornea are only partially affected. If the unaltered indices of corneal irregularities – such as SRI and SDP – are taken into account, it may be assumed that LRIs can be considered safe, thus not causing significant irregularities in corneal morphology.⁹ Budak et al.,¹⁰ reported an absolute decrease in mean astigmatism by 44%, Bayramlar et al.,¹¹ as 52%, Kaufmann et al.,¹² as 25% and Carvalho et al.,¹³ as 50%. Average central corneal power was not significantly modified by LRIs, thus confirming the value of the coupling ratio of approximately 1:1 previously published. Previously, Lindstrom found a 1:1 coupling ratio when a straight 3 mm keratotomy or a 45°–90° arcuate keratotomy incision is performed, thus showing that coupling ratio depends on the length, location, and depth of incision.¹⁴

                  In study titled Effect of Limbal relaxing incisions during phacoemulsification surgery, the mean uncorrected distance visual acuity (UDVA) and the best corrected visual acuity (BCVA) demonstrated statistically significant improvement after surgery. At the end of the follow-up period, the UCVA was statistically better for the patients with LRIs. ¹⁵ The LRIs group showed significant reduction in the mean topographic astigmatism from 1.48 ± 0.35 D preoperatively to 0.37 ± 0.14 D postoperatively (P < .0001) after one month. The mean magnitude of the surgically induced astigmatism (SIA) read 0.416 ± 0.406 D and 0.254 ± 0.210D by the end of the 1^st, the 3^rd month postoperatively in LRIs group, which was slightly lower than the target-induced astigmatism (TIA). The difference in SIA between the LRI statistically significant by the end of the 1^st and 3^rd month postoperatively (P < 0.001). The mean correction index (CI) was less than 1, which indicated under- correction effect of limbal relaxing incision. No difference was observed in the postoperative endothelial cell count between the two groups. There was no intraoperative and postoperative ocular or systemic complication.¹⁶ Different techniques are available to correct astigmatism, such as arcuate keratotomy, limbal relaxing incisions, laser vision correction, and Toric Implantable Collamer Lens (TICL) implantation. One popular approach to correct corneal astigmatism simultaneously to cataract surgery is to treat pre-existing astigmatism by creating limbal relaxing incisions. The limbal relaxing incisions (LRIs) technique involves the placement of incisions corresponding to the steep meridian, resulting in corneal flattening and the reduction of astigmatic power. LRI is a safe and an inexpensive procedure, which is simple for experts to perform. It can effectively reduce astigmatism up to 2.0 D and result in a rapid visual rehabilitation. Although the LRI astigmatism correcting capability was affirmed, vector analysis with the SIA lower than TIA and CI < 1, which means under-correction effect of limbal relaxing incision. As a method that is less dependent on the surgeons’ technical experience. The potential drawbacks of corneal incisions include risk of perforation, infection, unpredictability of results, creation of irregular astigmatism and disruption of the ocular surface as knowing that the regression of astigmatism can be as much as 1.00D, but in this study, it was found the regression of astigmatism would remain stable after 3 months postoperatively. Recently, the Toric hyperopic IOLs currently represents an alternative method to the incisional technique for the slight and moderate astigmatism during ICL surgery. However, the misalignment of the TICL might be a critical error.

CONCLUSION

Visual and refractive outcome changes as improved best corrected visual acuity (BCVA), decrease in Corneal Astigmatism was noted in patients undergoing limbal relaxing incision during clear corneal phacoemulsification surgery with foldable intra ocular lens. This technique is cheap, safe, quick, and helpful in reducing preexisting astigmatism till 2D and also in patients who are non-affording to pay for surgery with Toric lenses which is costly.

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