Prospective 12-month outcomes of combined iStent inject implantation and phacoemulsification in Asian eyes with normal tension glaucoma

BACKGROUND

Glaucoma is the leading cause of irreversible blindness. Normal tension glaucoma (NTG) is a subset of open-angle glaucoma, demonstrating glaucomatous optic nerve damage in the absence of raised intraocular pressure (IOP). NTG is more prevalent in Asian populations. While generally slow-progressing, NTG may be associated with significant central visual field loss. In recent years, minimally invasive glaucoma surgery has been added to the armamentarium of glaucoma surgery. This prospective study aims to evaluate 12-month surgical outcomes of combined iStent inject (Glaukos Corporation, Laguna Hills, CA) implantation and phacoemulsification in Asian eyes with NTG.

METHODS

This is a prospective, single-centre case series of 30 eyes followed up until 12 months after surgery. Outcome measures included IOP, number of glaucoma medications, best-corrected visual acuity (BCVA) and intra and postoperative complications.

RESULTS

Mean age of subjects was 73.1 ± 6.3 years. Majority were ethnic Chinese (n = 27, 90%). Baseline medicated mean IOP was 13.8 ± 2.4 mmHg and mean number of glaucoma medications was 1.3 ± 0.7. Mean Humphrey visual field mean deviation was - 13.7 ± 7.6. The mean IOP reduction at all timepoints from postoperative month (POM) 3 onwards was statistically significant (all P < 0.05), with mean reduction of 1.2 mmHg (95% CI: 0.1-2.2, P = 0.037) by POM12. There was statistically significant reduction in mean number of medications from postoperative day (POD) 1 onwards (all P < 0.05), with mean decrease of 1.0 medication (95% CI: 0.9-1.1, P < 0.001) by POM12. By POM12, 25 (83.3%) eyes were medication-free. Three (10%) eyes had stent occlusion by iris requiring laser iridoplasty. One eye had gross hyphema which resolved on conservative management before POM1. Mean BCVA improved from the baseline 0.3 ± 0.3 logMAR to 0.1 ± 0.1 logMAR postoperatively (P < 0.001). There were no major adverse or sight-threatening events. No eyes required further glaucoma surgery during the 12-month follow-up period.

CONCLUSION

Asian eyes with NTG which underwent combined iStent inject implantation and phacoemulsification demonstrated a significant and sustained reduction in IOP and glaucoma medications, up to 12 months postoperatively.

The role of lens extraction in glaucoma management

Cataract extraction has become a much safer procedure with the development of phacoemulsification, extending its application in ocular conditions such as glaucoma for better disease control. This review aims at summarizing the effect of lens extraction with or without combined glaucoma surgeries in different types of glaucoma and describing the intraoperative techniques and changes of glaucoma care postoperatively. A comprehensive literature search was performed through Medline and PubMed, and 67 studies were selected for this review. In primary angle closure (PAC) diseases, studies have revealed significant intraocular pressure (IOP) and medication requirement reduction after lens extraction. Fewer studies described its application in primary open angle glaucoma (POAG) and ocular hypertension (OHT), but literature available suggests that it can also lead to better disease control. Likewise, lower postoperative IOP and pressure fluctuations have been shown in normal tension glaucoma (NTG). Advanced glaucoma, shallow anterior chamber and pseudoexfoliation glaucoma (PXG) are three difficult scenarios that are commonly encountered in cataract operations. Special techniques in preventing complications such as wipe out phenomenon are depicted. Goniosynechialysis, endoscopic cyclophotocoagulation and trabecular microbypass stents are a few of the popular choices of glaucoma procedures that can be performed concomitantly with phacoemulsification but evidence of their efficacy needs to be further verified. Cataract operation can improve visual field and retinal nerve fiber layer examination parameters and it is advised to set new baselines after the surgery for subsequent progression monitoring. Clearance of an optically significant cataract results in better quality of life, and with detailed and thorough explanation of the indications, expectations and risks of the surgery, cataract extraction could be considered even in cases of advanced glaucoma.

Short-Term and Long-Term Variability of Intraocular Pressure Measured with an Intraocular Telemetry Sensor in Patients with Glaucoma

PURPOSE

To evaluate the short-term and long-term variability of intraocular pressure (IOP) in eyes with primary open-angle glaucoma.

DESIGN

Prospective study.

PARTICIPANTS

Twenty-two patients previously implanted with a sulcus-based IOP sensor (EyeMate, Implandata GmbH, Germany).

METHODS

Twenty-two patients previously implanted with the EyeMate were requested to obtain at least 4 IOP measurements daily. Data were grouped according to the eye and the medication so that an eye treated with a particular medication was considered as one group, and the same eye treated with a different medication during the observation period was considered as a different group. A day was divided into 7 periods: night, midnight to 5:59 am; early, 6 am to 7:59 am; morning, 8 am to 10:59 am; noon, 11 am to 1:59 pm; afternoon, 2 pm to 5:59 pm; evening, 6 pm to 8:59 pm; and late, 9 pm to 11:59 pm. Short-term variability during a particular period was defined as the variability in IOP measurements obtained during that period on different days within 3 months of each other. Long-term variability was defined as the variability in IOP measurements obtained during a particular period on different days over a period of 1 year or more. Variability was assessed using intraclass correlation coefficients (ICCs).

RESULTS

The mean age of study participants was 67.8 ± 6.8 years and 36.4% were women. The mean follow-up duration of patients was 19.2 ± 21.3 months (median, 9 months; range, 1-58 months). Overall, 92 860 IOP measurements over 15 811 measurement days were obtained and analyzed during the study period. The number of measurements obtained from each eye ranged from 1 daily to 277 daily. Intraclass correlation coefficients for short-term variability among the 7 periods during the day ranged from 0.52 (morning) to 0.66 (early). Long-term ICCs ranged from 0.29 (night) to 0.51 (late).

CONCLUSIONS

Continual IOP monitoring showed that IOP has moderate short-term and high long-term variability in glaucoma patients. These findings demonstrate that single IOP measurements do not characterize day-to-day variations in IOP. Moreover, they show the importance of continual IOP monitoring in glaucoma patients.

Can a contact lens sensor predict the success of trabectome surgery?

PURPOSE

We examined whether a contact lens sensor (CLS) is useful for the postoperative evaluation of trabectome surgery. We investigated the correlations between the outcomes of trabectome surgery and the output of a CLS.

METHODS

We examined 24 consecutive eyes of patients with pseudo-exfoliation glaucoma. In each eye, the intraocular pressure (IOP) fluctuations over 24 h were measured with the SENSIMED Triggerfish CLS before and at 3 months after the trabectome surgery. We divided the patients into success (n = 12 eyes) and failure (n = 12 eyes) groups; success was defined as a postoperative IOP level ≤ 21 mmHg plus an IOP reduction ≥ 20% relative to the preoperative IOP value with or without anti-glaucoma medications. We investigated CLS parameters that correlate with surgical outcomes by performing a Cox hazard regression analysis. We determined the maximum value, minimum value, and range of IOP fluctuation as CLS parameters.

RESULTS

The mean follow-up period was 38.0 ± 3.0 months. The success rate was 50%. The postoperative range of IOP fluctuation during the nocturnal period with the CLS was significantly correlated with the surgical results (p = 0.024).

CONCLUSIONS

A smaller range of IOP fluctuation was significantly correlated with better surgical outcomes. We were able to predict the surgical success after trabectome surgery at 3 months using the CLS. Thus, CLS results could be a new surgical evaluation parameter.