TNOA Journal of Ophthalmic Science and Research

ORIGINAL ARTICLE
Year
: 2022  |  Volume : 60  |  Issue : 3  |  Page : 232--234

Safety and efficacy of selective laser trabeculoplasty in secondary ocular hypertension following deep anterior lamellar keratoplasty


Premanand Chandran, Vinoth Arunaachalam, Mrunali Dhavalikar, Menaka Vimalanathan, Ganesh V Raman 
 Department of Glaucoma, Aravind Eye Hospital, Coimbatore, Tamil Nadu, India

Correspondence Address:
Premanand Chandran
Aravind Eye Hospital, Avinashi Road, Coimbatore, Tamil Nadu – 641 014
India

Abstract

Purpose: To evaluate the safety and efficacy of selective laser trabeculoplasty (SLT) in eyes with secondary ocular hypertension (OHT) following deep anterior lamellar keratoplasty (DALK). Methods: Retrospective review of patients who underwent SLT for increased intraocular pressure (IOP) following DALK between January 2014 and December 2016. Patients with a minimum follow-up of one year were included. Results: A total of seven eyes (seven patients) were analysed. The mean IOP reduced from 24.6 ± 11.1 to 15.3 ± 3.2 (p = 0.04), 14.2 ± 1.3 (P = 0.15) and 14 ± 1.4 (P = 0.09) mm Hg at one, two, and three years post-SLT respectively. The mean number of antiglaucoma medications (AGMs) reduced from 2.3 ± 1.1 to 0.2 ± 0 at one year, and 0 ± 0 at two and three years (P < 0.05). All eyes had clear graft during the entire follow-up, and there was no inflammation or signs of rejection post-SLT. Conclusions: SLT reduces IOP as well as the number of AGMs in eyes with OHT following DALK.



How to cite this article:
Chandran P, Arunaachalam V, Dhavalikar M, Vimalanathan M, Raman GV. Safety and efficacy of selective laser trabeculoplasty in secondary ocular hypertension following deep anterior lamellar keratoplasty.TNOA J Ophthalmic Sci Res 2022;60:232-234


How to cite this URL:
Chandran P, Arunaachalam V, Dhavalikar M, Vimalanathan M, Raman GV. Safety and efficacy of selective laser trabeculoplasty in secondary ocular hypertension following deep anterior lamellar keratoplasty. TNOA J Ophthalmic Sci Res [serial online] 2022 [cited 2022 Dec 10 ];60:232-234
Available from: https://www.tnoajosr.com/text.asp?2022/60/3/232/357115


Full Text



Selective laser trabeculoplasty (SLT) effectively lowers intraocular pressure (IOP) in patients with ocular hypertension (OHT) and open-angle glaucoma.[1] IOP lowering effect of SLT is equivalent to argon laser trabeculoplasty (ALT) in spite of using less than 1% energy required for ALT. SLT targets the melanin granules in the trabecular meshwork cells thereby stimulating cell division and recruitment of macrophages due to the release of cytokines (interleukin-1 and tumour necrosis factor α) that causes remodelling of extracellular matrix, allowing increased aqueous outflow.[2]

Incidence of OHT was reported to be 36.1% and glaucoma was 4.48% after deep anterior lamellar keratoplasty (DALK).[3] IOP reduction is of foremost importance as it helps in long-term survival of the graft. Topical AGMs are the first line of treatment for reducing IOP, but the concerns associated with its daily usage were the adherence to therapy, ocular and systemic side effects, cost and influence on the quality of life. SLT, apart from reducing the IOP, also helps in reducing the side effects associated with drops, cost of treatment and decreases the burden of installing drops on a daily basis, thereby improving the quality of life.[4],[5],[6] To our knowledge, there is no report on the effect of SLT on reducing IOP in eyes following DALK.

 Materials and Methods



We retrospectively reviewed the charts of all patients who underwent SLT for increased IOP following DALK between January 2014 and December 2016 at a tertiary eye care centre. Patients with a minimum follow-up of one year were included in the study. The study was approved by the Institute Ethics Committee and adhered to the tenants of the Declaration of Helsinki.

SLT was performed using a frequency-doubled, q-switched 532 nm Nd: YAG laser with a spot size of 400 μm and pulse duration of 3 ns (Selecta II, Lumenis, Dreieich, Germany). The laser energy was set to 0.8 mJ to begin with and then based on the response, the energy was increased or reduced in steps of 0.1 mJ till the appearance of fine champagne bubbles. All eyes underwent 360°C treatment with the use of a Latina lens. After the procedure the IOP was checked after 1 hr and the patient was asked to review after two weeks. Based on the IOP during the follow-up visit, the decision to stop the AGM was made. IOP was measured using Goldmann applanation tonometer. In eyes with high astigmatism two readings (horizontal and vertical) were measured, and the average was considered as the IOP. The success of the procedure was defined as IOP <21 mm Hg without medication or reduction of IOP by >20% from baseline.

Statistical analysis included mean and standard deviation (SD) for continuous variables. Paired t-test was used to compare the pre- and post-laser IOP and AGM. P < 0.05 was considered to be statistically significant. Statistical analysis was performed using commercial software (Stata ver. 13.1; StataCorp, College Station, Tx).

 Results



Seven eyes of seven patients met the inclusion criteria. All seven eyes underwent DALK for keratoconus. The mean age ± SD at presentation was 20.3 ± 3.1 years (range: 16, 33). Five patients were male and two were female. The mean follow-up period was 30 months (range; 12, 48). The mean best-corrected visual acuity was 6/12. The mean IOP at the time of presentation was 30.7 ± 6.7 mm Hg. The mean time interval between DALK and increase in IOP was 158 days (range: 42, 563). Angles were open in all eyes, and there was increased pigmentation of the trabecular meshwork in the eye that underwent DALK compared to the other eye of the patient. Optic disc and visual fields were normal in all the eyes.

The mean pre-laser IOP reduced from 24.6 ± 11.1 to 14.7 ± 3.7 at one month (P = 0.04), 15.3 ± 4.8 at three months (P = 0.06), 14.8 ± 3 at six months (P = 0.04), 15.3 ± 3.2 at one year (P = 0.04), 14.2 ± 1.3 at two years (P = 0.15) and 14 ± 1.4 mm Hg at three years (P = 0.09) post-SLT [Figure 1]. The mean number of AGM reduced from 2.3 ± 1.1 to 0.8 ± 1.3 at one month, 0.6 ± 0.8 at three months, 0.3 ± 0.4 at six months, 0.2 ± 0 at one year, and 0 ± 0 at two and three years (P < 0.05). [Table 1] summarizes the comparison of outcome measures pre- and post-SLT. The mean number of laser spot application was 90 ± 22 (range: 61, 120). The percentage of success as per the IOP <21 mm Hg without medication criteria was 85% at one, two, and three years. The percentage of success as per the >20% IOP reduction criteria was 100% at one, two, and three years. None of the eyes had a complication during or after the procedure.{Figure 1}{Table 1}

 Discussion



Incidence of glaucoma after DALK (0–17%) was reported to be less compared to penetrating keratoplasty (9–35%).[7],[8] Steroid usage, graft size mismatch, and pre-existing glaucoma were reported to be the common cause for glaucoma in patients undergoing DALK.

In our series none of the eyes had glaucoma prior to DALK, and there was no graft size mismatch. All eyes in our series were on topical prednisolone acetate 1% at the time of presentation with increased IOP and continued to have high IOP despite shifting to loteprednol etabonate 0.5%. Loteprednol is an ester corticosteroid which has less ocular hypertensive response compared to other ketone steroids.[9] It was also reported to be safe in the eyes after corneal transplantation without increasing the risk of graft rejection.[10] The reason for the non-reduction of IOP after shifting to loteprednol in our series could be the long -term usage of prednisolone which resulted in permanent damage to the trabecular meshwork. We also have noticed increased trabecular meshwork pigmentation in the eyes which have undergone DALK as compared to their fellow eyes, which could be due to long-term usage of steroids and/or pigment release during the procedure.

All patients in our study had secondary OHT. IOP reduction with SLT has been reported to range from 6.9 to 35.9%.[1] In our study, mean IOP reduction at one year was 34%, which is comparable to 35.9% reported by Tokuda et al.[11] and better than 21.9% reported by Gracner et al.[12] The probable reason for better IOP control in our study as compared to Gracner et al. could be 360°C treatment in all the eyes. IOP was controlled with SLT in all eyes except one which required 1 AGM for the IOP control. Even though there was 26% and 34% IOP reduction at two and three years post-SLT, it was not statistically significant, probably due to the small sample size. None of the eyes required a repeat laser or progressed to glaucoma. All eyes had clear graft during the entire follow-up, and there was no inflammation or signs of rejection after SLT.

Limitations of our study were its retrospective nature, small sample size, and varying number of laser spots applied. The number of laser spots applied varied widely between eyes due to the poor visibility of angle structures in a few eyes.

 Conclusion



SLT reduces IOP significantly as well as decreases the need for AGM in eyes with secondary OHT following DALK without compromising the graft.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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