The Effect of Corneal Refractive Surgery on Glaucoma

Comparison of Three Tonometers in Measuring Intraocular Pressure in Eyes That Underwent Myopic Laser in situ Keratomileusis and Photorefractive Keratectomy

Objective

Methods

Results

Conclusion

Intraocular pressure after myopic laser refractive surgery measured with a new Goldmann convex prism: correlations with GAT and ORA

Background

The purpose of this study is to describe measurements using a newly developed modified Goldmann convex tonometer (CT) 1 year after myopic laser refractive surgery. Intraocular pressure (IOP) measurements were compared with IOP values obtained by Goldmann applanation tonometer (GAT), and Ocular Response Analyzer (ORA).

Methods

Prospective double-masked study performed on thirty eyes of thirty patients that underwent laser in situ keratomileusis (LASIK; n = 19) or photorefractive keratectomy (PRK; n = 11). IOP was measured before and 3 and 12 months after surgery. Intraclass correlation coefficient (ICC) and Bland-Altman plot were calculated to assess the agreement between GAT, CT, IOPg (Goldmann-correlated IOP) and IOPcc (corneal-compensated IOP) from ORA.

Results

Twelve months after LASIK, IOP measured with CT showed the best correlation with IOP measured with GAT before surgery (GATpre) (ICC = 0.886, 95% CI: 0.703–0.956) (15.60 ± 3.27 vs 15.80 ± 3.22; p < 0.000). However, a moderate correlation was found for IOP measured with IOPcc and CT 12 months after LASIK (ICC = 0.568, 95% CI: − 0.185 – 0.843) (15.80 ± 3.22 vs 12.87 ± 2.77; p < 0.004). Twelve months after PRK, CT showed a weak correlation (ICC = − 0.266, 95% CI: − 3.896 – 0.663), compared to GATpre (17.30 ± 3.47 vs 16.01 ± 1.45; p < 0.642), as well as poor correlation (ICC = 0.256, 95% CI: − 0.332 – 0.719) with IOPcc (17.30 ± 3.47 vs 13.38 ± 1.65; p < 0.182).

Conclusions

Twelve months after LASIK, IOP measured with CT strongly correlated with GAT before surgery and could therefore provide an alternative method for measuring IOP after this surgery. More studies regarding this new convex prism are needed to assess its accuracy.

Acquired Optic Pits Associated with Laser-assisted In Situ Keratomileusis: A Case Series

Purpose

To present an association between acquired pits of the optic nerve (APON) and prior laser-assisted in situ keratomileusis (LASIK).

Materials and methods

A retrospective case series of patients with an optic disc pit on clinical exam and a history of LASIK. Spectralis Optical Coherence Tomography images and Humphrey Visual Fields were reviewed from prior visits. Extended-depth optical coherence tomography was performed of the optic nerve head at subsequent visits after patients were identified.

Results

Seven patients, aged 45-73 years, were identified each with unilateral optic disc pits. Optic disc pits were located inferior in six patients and centrally in one patient. All demonstrated thinning on optical coherence tomography and six patients had corresponding visual field defects. Four patients identified these defects after their LASIK procedure while two patients were unaware of their reproducible visual field defects. All patients were treated with drops initially. One patient underwent laser trabeculoplasty, and three underwent a trabeculectomy after demonstrating progression on maximum tolerated medical therapy.

Conclusion

This series describes a possible association between LASIK and APON. Given the similarity and severity of vision loss associated with the optic nerve pits in these patients after LASIK, increased awareness and caution is suggested while considering LASIK in susceptible individuals.

How to cite this article

Smith AK, Bussel I, Ling J, et al. Acquired Optic Pits Associated with Laser-assisted In Situ Keratomileusis: A Case Series. J Curr Glaucoma Pract 2020;14(3):106-108.

Evaluation of Retinal Ganglion Cell Layer Thickness in the Early Period After Femtosecond LASIK Surgery

Objectives:

To evaluate the early effects of femtosecond laser-assisted in situ keratomileusis (LASIK) surgery on retinal ganglion cell thickness (GCT), peripapillary retinal nerve fiber thickness (NFT), and central macular thickness (CMT) obtained by spectral domain optical coherence tomography (SD-OCT) in a healthy population.

Materials and Methods:

This case-control study included data from the right eye of 40 subjects without any disease other than refractive error and who had undergone femtosecond LASIK surgery. The preoperative, postoperative 1-hour, and postoperative 3-week GCT, NFT, and CMT values obtained by SD-OCT were compared.

Results:

The mean age was 27.54±5.99 years (18-45 years). GCT, NFT, and CMT were 18.43±6.03 μm, 107.90±9.01, and 234.3±21.2 μm preoperatively; 18.05±5.93 μm, 108.08±8.92 μm, and 230.1±22.6 μm at postoperative 1 hour; and 17.86±5.27 μm, 107.98±10.13, and 236.3±25.1 μm at postoperative 3 weeks (p=0.159, 0.85, and 0.254, respectively).

Conclusion:

There were no changes in GCT, NFT, and CMT values evaluated with SD-OCT in the early period after femtosecond LASIK surgery.

Intraoperative flap-related complications in FemtoLASIK surgeries performed with Visumax® femtosecond laser: A ten-year Romanian experience

Incidence and clinical results of intraoperative flap and interface-related complications were investigated after Femtosecond-LASIK surgery, where flap creation was performed with VisuMax^® femtosecond laser. A retrospective 10-year cohort study was conducted including all eyes treated for all refractive errors by Femtosecond-LASIK technique. All the flaps were made by the same refractive surgeon with the VisuMax^® (Carl Zeiss Meditec) femtosecond laser. We report the intraoperative flap and interface-related complications in these eyes, also describing their management. The study included 4,032 eyes. Flap and interface-related complications were: opaque bubble layer (OBL) 21.18%, suction loss 1.29%, difficult docking 0.69%, difficult dissection of the flap 0.59%, bleeding from limbal blood vessels 0.35%, de-epithelialization of the flap 0.12%, and interface debris 0.025%. These situations were appropriately addressed, with favorable outcomes. Flap creation is an important step in LASIK surgery. The predictability and safety have improved since the flap incision is assisted by a femtosecond laser, but complications of the flap and interface can still occur during the flap creation. Refractive surgeons should be aware and properly manage any unusual situation.

Glaucoma Progression and its Relationship with Corrected and Uncorrected Intraocular Pressure in Eyes with History of Refractive Corneal Surgery

PURPOSE

To investigate glaucoma progression and its relationship with corrected and uncorrected intraocular pressure (IOP) in patients with a history of refractive corneal surgery (RCS).

METHODS

Totally, 56 eyes of 56 primary open-angle glaucoma patients who had a history of RCS were included. Mean keratometry and central corneal thickness were measured at the time of glaucoma diagnosis. Three IOP measurements, i.e., uncorrected IOP (_UCIOP) and corrected IOP calculated by applying the Kohlhaas (_CKIOP) and Ehlers (_CEIOP) formulas, were used. Participants were categorized into two groups (low-teen [<15 mmHg] and high-teen [≥15 mmHg] groups) according to the mean follow-up IOP, in each of the three IOP measurements. Glaucoma progression was determined based on either structurally or functionally by stereoscopic optic disc/retinal nerve fiber layer photographs or visual field tests. Kaplan-Meier survival curves were compared between the low-teens group and high-teens group for each IOP measurement. Risk factors for glaucoma progression, including uncorrected and corrected IOP measurements, were analyzed using a Cox proportional-hazards model.

RESULTS

Among total eyes, glaucoma progression was found in 19 (34%) eyes during 4.3 years of mean follow-up period. Individual values of uncorrected IOP and corrected IOP showed significant differences (p < 0.001). Incidence of glaucoma progression was higher in high-teens group than in low-teens group by corrected IOP values (both Kohlhaas and Ehlers, p = 0.006, 0.003), but not by uncorrected IOP values (p = 0.749). The cumulative probability of glaucoma progression was significantly greater in the high-teens group than in the low-teens group using the Elhers formula determined by Kaplan-Meier analysis (p = 0.030).

CONCLUSIONS

For glaucoma eyes with history of RCS, high-teen group by corrected mean follow-up IOP showed more glaucoma progression than low-teen group. More intensive IOP-lowering treatment will be required for patient with high-teen follow-up corrected IOP to prevent glaucoma progression.