[show abstract][hide abstract] ABSTRACT: Purpose. Open angle glaucoma (OAG) is increasingly being viewed as an age-related neurodegenerative condition that may occur in individuals who are innately susceptible to global (autonomic) neural injury. Recent data support the plausibility of auditory neural impairment in a proportion of individuals with OAG, with results showing a key disruption to processing temporal properties of sound. This study tested the hypothesis that temporal processing deficits consistent with central (cortical) processing abnormalities are present in both the visual and auditory domains in individuals with glaucoma. Methods. A series of tasks designed to test progressively more complex aspects of temporal processing were conducted in 25 OAG individuals and 25 age- and sex-matched controls. For audition, baseline measurement of hearing sensitivity was followed by functional assessment of amplitude modulation detection, frequency discrimination at two reference levels, and speech perception. For vision, measures of foveal temporal contrast detection at two flicker rates, speed discrimination at two reference velocities, and coherent global motion detection were assessed. Results. A significant proportion of the OAG cohort displayed an impairment in auditory low-frequency discrimination, speech perception, visual speed discrimination for slow velocities and/or visual global motion detection, compared to controls (36%, 25%, 39%, and 34% respectively, were outside the 90th percentile of control performance; P < 0.05). Conclusions. A subgroup of individuals with OAG displayed impaired auditory temporal processing concurrent with signs of visual temporal processing impairment. These temporal processing deficits were in the presence of normal sound detection and normal central luminance increment thresholds.
[show abstract][hide abstract] ABSTRACT: Following the recent demonstration of increased mitochondrial DNA mutations in lymphocytes of POAG patients, the authors sought to characterize mitochondrial function in a separate cohort of POAG.
Using similar methodology to that previous applied to Leber's hereditary optic neuropathy (LHON) patients, maximal adenosine triphosphate (ATP) synthesis and cellular respiration rates, as well as cell growth rates in glucose and galactose media, were assessed in transformed lymphocytes from POAG patients (n = 15) and a group of age- and sex-matched controls (n = 15).
POAG lymphoblasts had significantly lower rates of complex-I-driven ATP synthesis, with preserved complex-II-driven ATP synthesis. Complex-I driven maximal respiration was also significantly decreased in patient cells. Growth in galactose media, where cells are forced to rely on mitochondrial ATP production, revealed no significant differences between the control and POAG cohort.
POAG lymphoblasts in the study cohort exhibited a defect in complex-I of the oxidative phosphorylation pathway, leading to decreased rates of respiration and ATP production. Studies in LHON and other diseases have established that lymphocyte oxidative phosphorylation measurement is a reliable indicator of systemic dysfunction of this pathway. While these defects did not impact lymphoblast growth when the cells were forced to rely on oxidative ATP supply, the authors suggest that in the presence of a multitude of cellular stressors as seen in the early stages of POAG, these defects may lead to a bioenergetic crisis in retinal ganglion cells and an increased susceptibility to cell death.
[show abstract][hide abstract] ABSTRACT: Background: To determine the prevalence of signs and symptoms of ocular surface disease in two hospital-based cohorts; glaucoma patients and non-glaucoma patients. Design: A cross-sectional, comparative case series. Participants: Glaucoma patients (n = 300) prescribed topical glaucoma medications for ≥6 months were compared with control patients (n = 100) who were not applying prescribed topical medications. Methods: A validated self-report questionnaire was used to elicit the extent of ocular symptoms. Signs of ocular surface and eyelid disease were assessed along with medication history. Main Outcome Measures: Signs and symptoms of ocular surface pathology were determined including the tear film break-up time, fluorescein staining of the cornea and conjunctiva, meibomian gland dysfunction and Schirmer's test. Results: A significant increase in the prevalence of ocular surface disease signs was observed in the glaucoma population, 70.3%, compared with controls, 33% (P < 0.001). The overall prevalence of clinically significant ocular surface disease symptoms was not significantly different between cohorts, 30.7% versus 24.0%, respectively (P = 0.252). Logistic regression analysis showed that the number of anti-glaucoma medications and duration of therapy were key predictors of significant ocular surface disease signs in the glaucoma group. There was no significant correlation between signs and symptoms of ocular surface disease in either group after adjusting for age and gender. Conclusions: Signs and symptoms of ocular surface disease are relatively common in older patients, but signs of ocular surface disease are significantly higher in individuals who instil topical glaucoma therapy.
Clinical and Experimental Ophthalmology 03/2012; 40(7):675-81. · 1.96 Impact Factor
[show abstract][hide abstract] ABSTRACT: The high energy demand of the auditory and visual pathways render these sensory systems prone to diseases that impair mitochondrial function. Primary open-angle glaucoma, a neurodegenerative disease of the optic nerve, has recently been associated with a spectrum of mitochondrial abnormalities. This study sought to investigate auditory processing in individuals with open-angle glaucoma. DESIGN/STUDY SAMPLE: Twenty-seven subjects with open-angle glaucoma underwent electrophysiologic (auditory brainstem response), auditory temporal processing (amplitude modulation detection), and speech perception (monosyllabic words in quiet and background noise) assessment in each ear. A cohort of age, gender and hearing level matched control subjects was also tested.
While the majority of glaucoma subjects in this study demonstrated normal auditory function, there were a significant number (6/27 subjects, 22%) who showed abnormal auditory brainstem responses and impaired auditory perception in one or both ears.
The finding that a significant proportion of subjects with open-angle glaucoma presented with auditory dysfunction provides evidence of systemic neuronal susceptibility. Affected individuals may suffer significant communication difficulties in everyday listening situations.
International journal of audiology 01/2012; 51(1):10-5. · 1.34 Impact Factor
[show abstract][hide abstract] ABSTRACT: The aims of this study are to investigate whether auditory dysfunction is part of the spectrum of neurological abnormalities associated with Leber's hereditary optic neuropathy (LHON) and to determine the perceptual consequences of auditory neuropathy (AN) in affected listeners. Forty-eight subjects confirmed by genetic testing as having one of four mitochondrial mutations associated with LHON (mt11778, mtDNA14484, mtDNA14482 and mtDNA3460) participated. Thirty-two of these had lost vision, and 16 were asymptomatic at the point of data collection. While the majority of individuals showed normal sound detection, >25% (of both symptomatic and asymptomatic participants) showed electrophysiological evidence of AN with either absent or severely delayed auditory brainstem potentials. Abnormalities were observed for each of the mutations, but subjects with the mtDNA11778 type were the most affected. Auditory perception was also abnormal in both symptomatic and asymptomatic subjects, with >20% of cases showing impaired detection of auditory temporal (timing) cues and >30% showing abnormal speech perception both in quiet and in the presence of background noise. The findings of this study indicate that a relatively high proportion of individuals with the LHON genetic profile may suffer functional hearing difficulties due to neural abnormality in the central auditory pathways.
Journal of Neurology 09/2011; 259(3):542-50. · 3.58 Impact Factor
[show abstract][hide abstract] ABSTRACT: To evaluate readability of eye drop labels and accurate recall of prescription instructions in a glaucoma population.
A hospital-based, cross-sectional study. A trained, interviewer examined patient ability to read standard and larger font medication labels. A questionnaire was administered to ascertain accurate recall of prescribed eye drops. Clinical information was obtained through independent chart review. Glaucoma severity was classified according to a glaucoma staging system. The setting for the study was the glaucoma outpatient clinic, Royal Victorian Eye and Ear Hospital (Melbourne, Australia), a major tertiary referral centre. A total of 200 glaucoma patients (96.2% response), aged 45-90 years, on eye drops took part in the study. Non-English-speaking patients were excluded. The main outcome measure was the ability to read prescribed medication labels and accurately recall treatment regime was compared with glaucoma severity and the number of eye drops.
Of the glaucoma patients, 12% were unable to read standard pharmacy labels. Only 5.5% were unable to read the larger font labels. Of the patients, 32% were not able to accurately recall the type of drops or prescribed frequency of instillation. An inability to read standard labels was associated with a threefold reduction in the likelihood of accurate medication recall (95% confidence intervals, 1.40-7.66, P < 0.05). Patients with three or more types of eye drops were five times less likely to recall their medications (95% confidence interval, 0.07-0.57, P < 0.05).
Inability to read or recall prescribed eye drops was associated with glaucoma severity and the number of prescribed eye drops. These factors may impact significantly on patients' adherence to glaucoma medications.
Clinical and Experimental Ophthalmology 12/2009; 37(9):849-54. · 1.96 Impact Factor
[show abstract][hide abstract] ABSTRACT: The case of a 78-year-old man with progressive glaucoma despite seemingly adequate control of his intraocular eye pressure is presented. On further questioning he was discovered to have played the trumpet for up to 4 h per day for 60 years. Significant increases in intraocular pressure were subsequently recorded during trumpet playing.
[show abstract][hide abstract] ABSTRACT: To investigate the effect of topical prostaglandin analogue use on the efficacy of selective laser trabeculoplasty (SLT) intraocular pressure (IOP) lowering in patients with open-angle glaucoma.Patients and
This retrospective study included 123 consecutive patients who underwent 180 degrees SLT for the first time. Eyes were grouped into those that received prostaglandin analogues before and after SLT (n=74) and those that did not (n=49). The main outcome measure was IOP lowering after SLT. Success was defined as > or =20% reduction in IOP without further glaucoma intervention.
There was no significant difference in IOP lowering at 6 months post-laser between the prostaglandin and non-prostaglandin groups (3.9+/-4.8 vs 4.6+/-3.6 mm Hg, P=0.43). Long-term SLT success rates were also not significantly different between the treatment groups (Kaplan-Meier survival analysis, P=0.68). IOP lowering at 6 months was similar in eyes that received no glaucoma medications, monotherapy with or without a prostaglandin analogue, or combination therapy with or without prostaglandin analogues (P=0.81). Logistic regression analysis showed that various patient characteristics including age, sex, type of glaucoma, previous glaucoma surgery, and other glaucoma risk factors did not predict a successful SLT outcome. However, higher pre-operative IOP was found to predict SLT success (odds ratio=1.12, 95% CI=1.02-1.24, P=0.02).
The IOP lowering efficacy of SLT is not influenced by the use of topical prostaglandin analogues.