Glaucoma surgery and induced astigmatism: a systematic review.

BACKGROUND: The refractive outcomes of glaucoma surgeries, particularly their effect on astigmatism, are incompletely understood. MAIN BODY: Trabeculectomy is associated with a considerable amount of with-the-rule astigmatic change in the immediate postoperative period. This is followed by a gradual against-the-rule shift. These changes are altered with the use of mitomycin C (MMC). Non-penetrating surgery such as deep sclerectomy is also associated with a similar or smaller degree of induced astigmatism. Minimally invasive glaucoma surgery appears to be astigmatically neutral. There is no clear evidence regarding refractive outcomes of glaucoma drainage device surgery. CONCLUSIONS: Induced astigmatism may account for a reduction in unaided visual acuity in the early postoperative period following a successful trabeculectomy. These changes appear to stabilise at 3 months, and it would be prudent to defer the prescription of new glasses until this time. If sequential cataract surgery is to be performed, toric intraocular lenses can be a useful option for astigmatic correction.

An acute intraocular pressure challenge to assess retinal ganglion cell injury and recovery in the mouse.

We describe a model of acute intraocular pressure (IOP) elevation in the mouse eye that induces reversible loss of inner retinal function associated with oxidative stress, glial cell activation and minimal loss of retinal ganglion cell (RGC) number. Young healthy mouse eyes recover inner retinal function within 7-days but more persistent functional loss is seen in older mice. Manipulation of diet and exercise further modify RGC recovery demonstrating the utility of this injury model for investigating lifestyle and therapeutic interventions. We believe that systematic investigation into the characteristics and determinants of RGC recovery following an IOP challenge will shed light on processes that govern RGC vulnerability in the early stages of glaucoma.

Glaucomatous optic neuropathy evaluation project: factors associated with underestimation of glaucoma likelihood.

IMPORTANCE: Glaucoma is a significant health problem for which diagnosis remains suboptimal. Optic disc evaluation, which is fundamental to the diagnosis, is a difficult skill to acquire. OBJECTIVES: To determine the optic disc characteristics that most influence decision making in the assessment of glaucoma likelihood and to ascertain the optic disc features associated with overestimation and underestimation of glaucoma likelihood. DESIGN, SETTING, AND PARTICIPANTS: This prospective, observational, Internet-based study with multinational participation included 197 ophthalmic clinicians (37 glaucoma subspecialists, 51 comprehensive ophthalmologists, and 109 ophthalmology trainees) from 22 countries who self-registered for the Glaucomatous Optic Neuropathy Evaluation (GONE) Project from December 1, 2008 through June 30, 2010. INTERVENTIONS: A series of 42 monoscopic optic disc photographs of healthy and glaucomatous eyes were presented to clinicians using the GONE Project Program. Participants were asked to assess each disc according to 9 conventional topographic features and assign a presumptive grade for glaucoma likelihood. MAIN OUTCOMES AND MEASURES: Agreement (κ and weighted κ) among participants for disc signs and glaucoma likelihood and contributions of disc-related factors to overestimation and underestimation of glaucoma likelihood. RESULTS: Ophthalmology trainees and comprehensive ophthalmologists underestimated glaucoma likelihood in a mean (SD) of 22.1% (1.6%) and 23.8% (1.8%) of discs, respectively. Underestimation of vertical cup-disc ratio and failure to identify retinal nerve fiber layer loss, disc hemorrhage, or rim loss were most likely to lead to underestimation of glaucoma. When all 4 features were inaccurately assessed, underestimation of glaucoma likelihood increased to 43.0%. Ophthalmology trainees and comprehensive ophthalmologists overestimated glaucoma likelihood in a mean (SD) of 13.0% (1.2%) and 8.9% (1.3%) of discs, respectively. Overestimation of glaucoma likelihood was associated with overestimation of retinal nerve fiber layer loss, rim loss, vertical cup-disc ratio, disc hemorrhage, and incorrect assessment of disc tilt and was more likely in large discs. CONCLUSIONS AND RELEVANCE: Ophthalmology trainees and comprehensive ophthalmologists underestimated glaucoma likelihood in approximately 1 in 5 disc photographs and were twice as likely to underestimate as overestimate glaucoma likelihood. Underestimating the vertical cup-disc ratio and cup shape and missing retinal nerve fiber layer defects and disc hemorrhage were the key errors that led to underestimation. When all 4 parameters were incorrectly assessed, underestimation increased to almost 1 in 2.

Glaucomatous optic neuropathy evaluation (GONE) project: the effect of monoscopic versus stereoscopic viewing conditions on optic nerve evaluation.

PURPOSE: To determine whether monoscopic vs stereoscopic viewing impacts evaluation of optic disc photographs for glaucoma diagnosis in an expert population. DESIGN: Prospective observational study. METHODS: Twenty pairs of high-quality monoscopic and stereoscopic photographs of similar size and magnification (ie, 40 images), were selected to demonstrate a range of optic disc features from a total of 197 eyes of 197 patients with glaucoma and normal subjects recruited from a tertiary clinic. These were presented in randomized order via an interactive platform (http://stereo.gone-project.com/). Participants assessed 9 topographic features and estimated glaucoma likelihood for each photograph. Main outcome measures were intra- and inter-observer agreement. RESULTS: There was good intra-observer agreement between monoscopic and stereoscopic assessments of glaucoma likelihood (κw = 0.56). There was also good to substantial agreement for peripapillary atrophy (κw = 0.65), cup shape (κw = 0.65), retinal nerve fiber layer loss (κw = 0.69), vertical cup-to-disc ratio (κw = 0.58), and disc shape (κw = 0.57). However, intra-observer agreement was only fair to moderate for disc tilt, cup depth, and disc size (κw = 0.46-0.49). Inter-observer agreement for glaucoma likelihood in monoscopic photographs (κw = 0.61, 95% confidence interval [CI] = 0.55-0.67) was substantial and not lower than in stereoscopic photographs (κw = 0.59, CI = 0.54-0.65). Monoscopic photographs did not lead to lower levels of inter-observer agreement compared to stereoscopic photographs in the assessment of any optic disc characteristics, for example disc size (mono κw = 0.65, stereo κw = 0.52) and cup-to-disc ratio (mono κw = 0.72, stereo κw = 0.62). CONCLUSIONS: For expert observers in the evaluation of optic disc photographs for glaucoma likelihood, monoscopic optic disc photographs did not appear to represent a significant disadvantage compared to stereoscopic photographs.

Glaucomatous optic neuropathy evaluation project: a standardized internet system for assessing skills in optic disc examination.

BACKGROUND: Development of a standardized internet-based system to self-assess skills in optic disc examination for glaucoma risk assessment. DESIGN: Prospective internet-based observational study. PARTICIPANTS: Total of 197 participants (glaucoma subspecialists, general ophthalmologists and trainees) from 22 countries. METHODS: Forty-two optic disc images demonstrating a range of features were selected from 2500 monoscopic disc photographs of normal and glaucomatous eyes. Images were presented to clinicians via website (http://www.gone-project.com). Participants were asked to assess nine topographic features and make a subjective assessment of glaucoma likelihood. MAIN OUTCOME MEASURES: Inter-observer agreement using kappa (κ) or weighted kappa (κ(w) ). RESULTS: There was substantial level of inter-observer agreement between glaucoma subspecialists for assessment of glaucoma likelihood (κ(w) = 0.63). Inter-observer agreement was high for haemorrhage (κ= 0.83) and substantial for disc size, disc shape, cup:disc ratio, peripapillary atrophy and cup shape (κ(w) = 0.59-0.68). Subspecialists had stronger inter-observer agreement for glaucoma likelihood and for most disc characteristics than did trainees: the greatest difference being the assessment for retinal nerve fibre layer loss. Analysis of individual disc answers from ophthalmology trainees showed that discs leading to lower agreement of glaucoma likelihood tend to produce lower agreement for the assessment of cup:disc ratio, cup shape, cup depth and retinal nerve fibre layer. Discs with features of moderate to deep cup or cup:disc ratio between 0.6 and 0.8 also lead to lower agreement in glaucoma likelihood. CONCLUSIONS: This internet-based system is a readily accessible and standardized tool, for clinicians globally, that permits self-assessment and benchmarking of skills in optic disc examination.