Associate Professor Mark Roth
BSc(Pharm) BAppSc(Optom) PGCertOcTher NECO FAAO OAM
Efficacy of corneal collagen cross-linking for keratoconus in children
A study published in the February issue of the journal Cornea confirms that corneal cross-linking (CXL) is effective in stabilising keratoconus for more than two years in most paediatric eyes.
To report the long-term outcome of corneal collagen cross-linking for progressive keratoconus in paediatric patients, researchers conducted epithelium-off CXL in paediatric eyes with progressive keratoconus. Spectacle-corrected distance visual acuity (CDVA), retinoscopy, topography and tomography were documented preoperatively and postoperatively at three months, six months, one year and annually thereafter.
A total of 377 eyes of 336 paediatric patients aged eight to 18 years with progressive keratoconus underwent CXL. Of these, 194 eyes had a follow-up beyond two years and up to 6.7 years. At last follow-up, there was significant improvement in mean CDVA from 0.33 +/- 0.22 to 0.27 +/- 0.19 logMAR (p <= 0.0001), reduction in mean topographic astigmatism from 7.22 +/- 3.55 to 6.13 +/- 3.28 D (p = 0.0001), mean flattening of 1.20 +/- 3.55 dioptres in maximum keratometry (Kmax) (p = 0.0002), and mean corneal thinning of 31.1 +/- 36.0 microns (p < 0.0001) after CXL.
The mean change in Kmax was most significant in moderately advanced keratoconus (average keratometry 48-53 dioptres). Central cones showed more corneal flattening than peripheral cones. Stabilisation or flattening of Kmax was seen in 85 per cent of eyes at two years and in 76 per cent after four years. Stabilisation or improvement of CDVA was seen in 80.1 per cent of eyes at two years and in 69.1 per cent after four years.
The authors concluded that CXL remains effective in stabilising keratoconus for longer than two years in a majority of paediatric eyes. Flattening of Kmax was greater in moderately advanced keratoconus and central cones; however, long-term follow-up beyond four years revealed that a few eyes showed features suggestive of a reversal of the effect of CXL.
Cornea 2017 Feb; 36: 2: 138-143; doi: 10.1097/ICO.0000000000001102
How often should the Goldmann Applanation tonometer be checked for calibration error?
According to a study published in the Journal of Glaucoma, twice a year, unless it’s more than one year old, then it should be checked monthly.
In a study to evaluate the frequency of Goldmann applanation tonometer (GAT) calibration errors, GATs were divided into three groups: group 1 (G1) is less than or equal to 1 year, group 2 (G2) >1 to 10 years, and group 3 (G3) > 10 years of usage. Tonometers were checked at baseline for calibration errors and defined as ‘faulty’ when calibration error exceeded 2 mmHg at any testing level. Faulty GATs were repaired in-house. Subsequent calibration error checks were conducted once per month for six months.
In total, 76 slit-lamp mounted GATs were included. The number of GATs in groups 1 to 3 was 19, 36, and 21, respectively. Seven (9.2 per cent) tonometers were faulty at the baseline. None in G1, five in G2, and 16 in G3 demonstrated unacceptable calibration errors over the study course (p < 0.01).
The survival function of G1 tonometers was 1.0 throughout, whereas those (95% confidence interval) of the G2 and G3 tonometers were 0.97 (0.81-0.99) and 0.76 (0.51-0.89) at one month, and 0.86 (0.69-0.93) and 0.23 (0.08-0.43) at six months, respectively.
The researchers concluded that the probability of calibration error increased with increasing age of the tonometer. The frequency of use of the tonometer was not associated with the development of calibration error.
J Glaucoma 2016 Nov; 25: 11: 908-913; doi: 10.1097/IJG.0000000000000545
Jardiance approved by US FDA for adults with type 2 diabetes
To reduce the risk of cardiovascular death in adult patients with type 2 diabetes mellitus and cardiovascular disease, the US Food and Drug Administration has approved a new indication for Jardiance (empagliflozin). The announcement was made in December 2016.
According to the Centers for Disease Control and Prevention, death from cardiovascular disease is 70 per cent higher in adults with diabetes compared to those without diabetes, and patients with diabetes have a decreased life expectancy driven in large part by premature cardiovascular death.
In Australia, Jardiance is available on the Pharmaceutical Benefits Scheme as an adjunct to diet and exercise to improve glycaemic control in adults with type 2 diabetes mellitus. It has not been approved in Australia for cardiovascular disease.
The FDA conducted a post-market clinical trial of more than 7,000 patients with type 2 diabetes and cardiovascular disease. In the trial, Jardiance was shown to reduce the risk of cardiovascular death compared to a placebo when added to standard of care therapies for diabetes and atherosclerotic cardiovascular disease.
Jardiance is not intended for patients with type 1 diabetes mellitus or for the treatment of diabetic ketoacidosis. Jardiance is contraindicated in patients with a history of serious hypersensitivity reactions to Jardiance, severe renal impairment, end-stage renal disease or dialysis.
SWAP vs OCT in the early detection of glaucoma
Researchers assessed the role and diagnostic efficacy of optical coherence tomography (OCT) and short wave automated perimetry (SWAP) to distinguish between normal subjects, glaucoma suspects and diagnosed glaucomatous eye.
In this randomised controlled, consecutive, prospective study, researchers divided 70 subjects (140 eyes) into three groups: group A: 10 healthy volunteers (20 eyes); group B: 30 glaucoma suspects (60 eyes); and group C: 30 subjects (60 eyes) with already diagnosed glaucomatous eyes.
Average retinal nerve fibre layer thickness was 75 ±9 microns in the glaucoma group; 99 ±15.5 microns in the control group; and 94 ±12 microns in glaucoma suspects. The early parameter affected was the inferior quadrant. Researchers detected significant correlation between visual field parameters and retinal nerve fibre layer thickness in glaucoma and glaucoma suspect groups.
The researchers noted that retinal nerve fibre layer defect can be difficult to identify during clinical examination, and early detection of glaucoma is still controversial, whether by OCT, SWAP or frequency-doubling technology perimetry.
The researchers concluded that while OCT parameters tended to be more sensitive than SWAP parameters, retinal nerve fibre layer thickness measured by OCT and SWAP indices were good discrimination tools between glaucomatous, glaucoma suspect and normal eyes.
Clin Ophthalmol 2016; 10: 1819-1824
Higher IOP associated with faster loss of RNFL
Higher intraocular pressure (IOP) was associated with faster rates of progressive retinal nerve fibre layer loss over three years, according to a cohort study published in Ophthalmology.
Researchers recruited 339 patients to two glaucoma studies at three different academic centres, and followed them for an average of 3.9 years. The mean age of patients at baseline was 65.8 years, and 53.4 per cent were women. Of these patients, 308 (56.3 per cent) had a diagnosis of glaucoma and 239 (43.7 per cent) were considered glaucoma suspects.
All eyes were imaged with SD OCT, with glaucoma progression defined as a result of likely progression on the SAP.
The researchers found the largest associations between IOP and retinal nerve fibre layer change rates in measurements from the temporal superior and temporal inferior sectors, and the smallest association for measurements from the nasal sector. For progressing eyes, OCT found that each 1 mmHg increase in IOP correlated with additional losses of 0.35 and 0.31 microns/year for the temporal superior and temporal inferior sectors of the eyes, respectively.
The authors concluded that their findings support the use of retinal nerve fibre layer thickness measurements obtained by SD-OCT in evaluating the efficacy of IOP-lowering therapies to slow the rate of disease progression, and suggested that these measurements may lead to a better understanding of the relationship between IOP and neural losses in glaucoma.
Ophthalmology 2016; 123: 10: 2058-2065
Caution urged with the use of bimatoprost after cataract surgery
The open-access journal Ophthalmological Medicine has published a case report on bimatoprost-induced serous macular detachment and choroidal folds following uneventful cataract surgery.
A 66-year-old male using topical bimatoprost in both eyes for open-angle glaucoma underwent uneventful cataract surgery in the right eye. Postoperatively, he was restarted on topical bimatoprost and antibiotic-steroids combination drops.
A week after surgery, he presented with conjunctival hyperaemia, serous macular detachment and choroidal folds at the posterior pole. Fundus fluorescein angiography showed perifoveal leaks in early stage with pooling of dye in late stage. Discontinuation of bimatoprost led to resolution of serous detachment and choroidal folds within three weeks with improvement in visual acuity.
The authors suggested that occurrence of serous macular detachment and choroidal folds in this case could be related to the proinflammatory property of bimatoprost. They added that bimatoprost should be used with caution in the immediate postoperative period after cataract surgery.
Case Rep Ophthalmol Med 2016; doi: 10.1155/2016/7260603
Povidone-iodine for bacterial keratitis in the developing world
Povidone-iodine 1.25% should be considered for the treatment of bacterial keratitis when antibiotic treatment is not practical, according to a study published in the American Journal of Ophthalmology.
The randomised, controlled, investigator-masked clinical trial compared povidone-iodine 1.25% ophthalmic solution with topical antibiotics for bacterial keratitis in areas where use of effective topical antibiotics may not be an option.
A total of 172 adults with bacterial keratitis were randomised to be treated with either povidone-iodine (40 patients in the Philippines, 38 in India) or the control antibiotic (49 patients in the Philippines, 45 in India).
Thirty patients out of 40 treated with povidone-iodine and 39 out of 49 treated with neomycin-polymyxin B-gramicidin in the Philippines achieved cure. In India, 12 individuals out of 38 treated with povidone-iodine and 10 individuals from 45 treated with ciprofloxacin achieved cure.
The researchers concluded that there is no significant difference between the effect of topical povidone-iodine 1.25% and topical antibiotics commonly available in the developing world for treatment of bacterial keratitis. Povidone-iodine 1.25%, which is widely available and inexpensive, can be considered for treatment of bacterial keratitis when antibiotic treatment is not practical.
The researchers added that the results are applicable to children as well, who are disproportionately affected by infectious keratitis in the developing world.
Am J Ophthalmol 2016; doi:10.1016/j.ajo.2016.10.004