Difference in intraocular pressure measurements between non-contact tonometry and Goldmann applanation tonometry and the role of central corneal thickness in affecting glaucoma referrals

BACKGROUND

Patients at glaucoma risk are commonly identified by optometrists and subsequently referred to glaucoma specialists. Optometrists mainly use non-contact tonometry (NCT) for intraocular pressure (IOP) measurement.

AIMS

To investigate the role of differences in IOP measurement between NCT and Goldmann applanation tonometry (GAT) and the effect of central corneal thickness (CCT) on these differences in optometrist referrals METHODS: Details of the initial clinical visit of patients referred with IOP > 21 mmHg in either eye as measured by NCT to a consultant glaucoma specialist were retrospectively reviewed. Demographic and referral data, IOP, CCT, and glaucoma diagnosis were obtained. The main outcome measure was the IOP measurement differences between NCT and GAT.

RESULTS

Of the 98 patients referred, only 23% had IOP > 21 mmHg when measured by GAT. NCT (Nidek NT400, Reichert Puff, Pulsair Easy Eye) measured the IOP greater than GAT by a mean of 5.8 mmHg (NCT 24.1 ± 3.5, GAT 18.3 ± 3.0). The effect of CCT on IOP measurement was less for GAT (R² 0.034, p = 0.067) than for NCT (R² 0.088, p = 0.003). The NCT/GAT IOP differences increased with increasing CCT (R² 0.166, p < 0.0001). The NCT/GAT differences decreased with patient age (R² 0.048, p = 0.03). Patients were classified as normal 67% (66/98), ocular hypertension 11% (11/98), glaucoma suspect 14% (14/98), and glaucoma 7% (7/98).

CONCLUSIONS

The difference in IOP measurement between NCT and GAT leads to a possible increase in glaucoma referrals, particularly in patients with thicker corneas. Repeat IOP using GAT and CCT measurement would help in triaging referrals.

Genetic association study of exfoliation syndrome identifies a protective rare variant at LOXL1 and five new susceptibility loci

Exfoliation syndrome (XFS) is the most common known risk factor for secondary glaucoma and a major cause of blindness worldwide. Variants in two genes, LOXL1 and CACNA1A, have previously been associated with XFS. To further elucidate the genetic basis of XFS, we collected a global sample of XFS cases to refine the association at LOXL1, which previously showed inconsistent results across populations, and to identify new variants associated with XFS. We identified a rare protective allele at LOXL1 (p.Phe407, odds ratio (OR) = 25, P = 2.9 × 10^-14) through deep resequencing of XFS cases and controls from nine countries. A genome-wide association study (GWAS) of XFS cases and controls from 24 countries followed by replication in 18 countries identified seven genome-wide significant loci (P < 5 × 10^-8). We identified association signals at 13q12 (POMP), 11q23.3 (TMEM136), 6p21 (AGPAT1), 3p24 (RBMS3) and 5q23 (near SEMA6A). These findings provide biological insights into the pathology of XFS and highlight a potential role for naturally occurring rare LOXL1 variants in disease biology.

Intermediate-term and long-term outcome of piggyback drainage: connecting glaucoma drainage device to a device in-situ for improved intraocular pressure control

IMPORTANCE

This study provides results of a treatment option for patients with failed primary glaucoma drainage device.

BACKGROUND

The study aimed to describe and evaluate the long-term intraocular pressure control and complications of a new technique joining a second glaucoma drainage device directly to an existing glaucoma drainage device termed 'piggyback drainage'.

DESIGN

This is a retrospective, interventional cohort study.

PARTICIPANTS

Eighteen eyes of 17 patients who underwent piggyback drainage between 2004 and 2013 inclusive have been studied. All patients had prior glaucoma drainage device with uncontrolled intraocular pressure.

METHODS

The piggyback technique involved suturing a Baerveldt (250 or 350 mm) or Molteno3 glaucoma drainage device to an unused scleral quadrant and connecting the silicone tube to the primary plate bleb.

MAIN OUTCOME MEASURES

Failure of intraocular pressure control defined as an intraocular pressure greater than 21 mmHg on maximal therapy on two separate occasions or further intervention to control intraocular pressure.

RESULTS

The intraocular pressure was controlled in seven eyes (39%) at last follow-up with a mean follow-up time of 74.2 months. The mean preoperative intraocular pressure was 27.1 mmHg (95% confidence interval 23.8-30.3) compared with 18.4 mmHg (95% confidence interval 13.9-22.8) at last follow-up. The mean time to failure was 57.1 months (95% confidence interval 32.2-82), and the mean time to further surgery was 72.3 months (95% confidence interval 49.9-94.7). Lower preoperative intraocular pressure was associated with longer duration of intraocular pressure control (P = 0.048). If the intraocular pressure was controlled over 2 years, it continued to be controlled over the long term. Two eyes (11%) experienced corneal decompensation.

CONCLUSIONS

Piggyback drainage represents a viable surgical alternative for the treatment of patients with severe glaucoma with failing primary glaucoma drainage device, particularly in those at high risk of corneal decompensation.

Factors that influence the patient uptake of diabetic retinopathy screening

AIM

To assess whether patients were receiving regular diabetic retinopathy screening and to examine factors influencing screening uptake.

METHODS

A questionnaire covering demographics, diabetic medical history and the knowledge of and attitudes to diabetic retinopathy was administered to all adults who were due to attend diabetes clinics in two centres in Dublin, Ireland over two months in 2001/2002.

RESULTS

Of the 209 people who completed the questionaire, 169 (81%) had a dilated fundal examination within the last year. The most significant predictor for receiving screening was a previous physician recommendation about the necessity of a regular eye examination. The main barriers to receiving adequate screening were lack of knowledge regarding the need for ocular examination and the effect of mydriasis in prohibiting driving.

CONCLUSIONS

It is essential that patients are fully aware of the need for a regular eye examination. Once a physician recommends this the screening rate improves.