Intraocular pressure changes following topical ocular hypotensive medications washout.

BACKGROUND: To review the changes in intraocular pressure (IOP) following topical hypotensive medications washout in patients with primary open angle glaucoma (POAG), ocular hypertension (OHT) and uveitic glaucoma (UG)/OHT. METHODS: The study included 120 patients with POAG, OHT and UG recruited from prospective clinical trials between February 2013 and July 2017. We excluded 20 eyes with IOP of ≤21 mm Hg, 11 eyes with previous incisional surgery and 17 eyes with incomplete data. UG eyes with active inflammation and on steroid treatment were excluded. Participants underwent a 1-month washout period from topical ocular hypotensive medications before IOP phasing. Comparisons were made between pre/post-washout IOP, and highest-recorded (peak) and post-washout IOP. RESULTS: A total of 110 eyes with POAG, 33 eyes with OHT and 43 eyes with UG were included for analysis. The mean pre-washout IOP was 18.1±3.3 mm Hg in POAG, 18.8±3.3 mm Hg in OHT and 17.9±8.8 mm Hg in UG; the mean post-washout IOP was 26.6±4.8 mm Hg, 26.4±3.9 mm Hg, 23.1±10.1 mm Hg in POAG, OHT and UG, respectively. The mean increase in IOP after washout was significantly lower in UG compared with POAG and OHT eyes (p=0.01). The percentage of eyes with post-washout IOP <22 mm Hg was 12.7% in POAG, 6.1% in OHT and 51.2% in UG. CONCLUSION: Active inflammation and steroid treatment contributes to elevated IOP in uveitis. Therefore, IOP may revert to normal once inflammation subsides. We recommend ocular hypotensive treatment washout to be considered in UG eyes that have IOP under control in the absence of recurrence of uveitis.

Predictors of selective laser trabeculoplasty success in open angle glaucoma or ocular hypertension: does baseline tonography have a predictive role?

BACKGROUND: The determinants of success of selective laser trabeculoplasty (SLT) in treatment-naïve patients with open angle glaucoma (OAG) and ocular hypertension (OHT) have not been understood fully. Therefore, we have conducted this study to explore the predictors of success. METHODS: This is a retrospective review of a pre-existing database of patients who had received primary SLT at St Thomas' Hospital, London, UK. Patients with OAG and OHT who had received primary 360° SLT treatment and had reliable baseline tonographic outflow facility (TOF) with minimum of 1 year of follow-up were included. Univariate and multivariate analyses were performed to find the determinants of success. RESULTS: One hundred and seventy-four patients between August 2006 and February 2010 had received primary 360° SLT treatment and had baseline TOF measurement. Of these, 72 subjects fulfilled the eligibility criteria. In multivariate regression analysis, the only variable associated with success was baseline intraocular pressure (IOP) (R2=0.32, beta=-0.51, p<0.001, 95% CI -2.02 to -0.74). CONCLUSION: To our knowledge, this is the only study investigating the pretreatment TOF (measured with electronic Shiøtz tonography) and IOP as determinants of success 12 month's post-360° SLT in treatment-naïve patients with OAG and OHT. This study demonstrated that pretreatment IOP (and not TOF) is the only determinant of success after primary SLT therapy.

Effect of phacoemulsification on facility of outflow.

PURPOSE: Phacoemulsification has been shown to reduce intraocular pressure (IOP). The mechanism of action is thought to be via increased trabecular outflow facility. However, studies on the relationship between phacoemulsification and outflow facility have been inconsistent. This study intended to examine the change in electronic Schiotz tonographic outflow facility (TOF) and IOP measurements following phacoemulsification. METHODS: Patients who were due to undergo a standard clear corneal incision phacoemulsification with intraocular lens (IOL) implantation, at St Thomas' Hospital, were invited to participate in this study. IOP was measured using Goldmann's applanation tonometer, and TOF was measured by electronic Schiotz tonography at baseline and at 3, 6 and 12 months postoperatively. RESULTS: Forty-one patients were recruited. Tonography data for 27 patients were reliable and available at all time points. Eleven cases had primary open angle glaucoma and cataract, while 16 patients had cataract only. Mean IOP reduced at every time point postoperatively significantly compared with baseline. TOF improved significantly after cataract extraction at all time points (baseline of 0.14±0.06 vs 0.18±0.09 at 3 months, P=0.02 and 0.20±0.09 at 6 months, P=0.003, 0.17±0.07 µL/min mmHg at 12 months, P=0.04). Five contralateral eyes of patients with cataracts only who did not have any intraocular surgery during the follow-up period were used as comparison. Their IOP and TOF did not change significantly at any postoperative visits. CONCLUSION: This is the first study using electronic Schiotz tonography with documented anterior chamber depth and gonioscopy after modern cataract surgery (CS) with phacoemulsification and IOL implantation. We demonstrated that phacoemulsification increases TOF and this fully accounts for the IOP reduction following CS. ISTCRN REGISTRATION NUMBER: ISRCTN04247738.