24-hour IOP Monitor Well-Tolerated in Trial

Staff
12/10/2012

An uncontrolled open trial of 10 healthy volunteers has reported encouraging results on the tolerability and functionality of an ocular telemetric sensor for 24-hour intraocular pressure-fluctuation monitoring. An orbital bandage containing a loop antenna and an 8.7-mm radius prototype ocular telemetry sensor were applied and connected to a portable recorder after full eye examination. Best-corrected visual acuity and position, surface wetting ability and mobility of the sensor were assessed after five and 30 minutes, and four, 12 and 24 hours. Subjective wearing comfort was scored and activities documented in a logbook. After sensor removal, a full eye examination was repeated and the recorded signal analyzed.

The comfort score was high and did not fluctuate significantly over time. The mobility of the sensor was limited across follow-up visits and its surface wetting ability remained good. BCVA was significantly reduced during sensor wear and immediately after its removal (from 1.07 before, to 0.85 after; p=0.008). Three subjects developed a mild, transient corneal abrasion. In all but one participant, researchers obtained usable data of a telemetric signal recording with sufficient sensitivity to depict ocular pulsation.
Smedt S, Mermoud A, Schnyder C.


Meibomian Gland Alterations With Antiglaucoma Eye Drops
Researchers from Japan have determined that long-term use of antiglaucoma eye drops is associated with alterations in meibomian gland morphology and function. The subjects were 162 eyes of 162 patients with primary open-angle glaucoma or normal tension glaucoma. Patients were broken into three groups based on the number of antiglaucoma drops administered: 71 eyes of 71 patients (Group 1) received one type of drop, 61 eyes of 61 patients (Group 2) received two types of drops and 30 eyes of 30 patients (Group 3) received three types of drops. There were 75 eyes of 75 healthy volunteers to serve as controls.

Subjective symptoms were evaluated by questionnaire, and lid margin and superficial punctate keratopathy were evaluated by slit-lamp examination. Meibomian glands of upper and lower eyelids were observed and scored using noncontact meibography (meiboscore). Tear-film breakup time was measured and meibum was graded. Results showed that lid margin abnormality, superficial punctate keratopathy, meiboscore and meibum scores were significantly higher in glaucoma patients than in controls (p<0.001). TFBUT and Schirmer scores were significantly lower in glaucoma patients than in controls (p<0.001). Subgroup analysis of the parameters in Group 1 revealed no significant difference between patients receiving prostaglandin and those receiving ß-blockers, or among Groups 1, 2 and 3. Multivariate regression analysis demonstrated that meiboscore significantly correlated with lid margin abnormality score (p=0.007) and TFBUT (p=0.045) in Group 1; with TFBUT (p=0.004), symptom score (p=0.003) and age (p=0.026) in Group 2; and with lid margin abnormality score (p=0.001) in Group 3.
Arita R, Kouzo I, Maeda S, Maeda K, et al. 


High Prevalence of Sleep Disorders in Patients with DME
British researchers indicate that while individuals with clinically significant diabetic macular edema have a high prevalence of sleep disordered breathing (SDB), it is unclear what mechanism of SDB contributes to the pathophysiology of CSME.

Eighty patients (40 men) with CSME had a home sleep study to identify SDB. The average patient age was 64.7 years, with a neck circumference of 40.4 cm, body mass index of 30.2 kg/m2, glycosylated hemoglobin (HbA1c) of 7.8 percent, and Epworth sleepiness scale of 7.4. Results were compared with relevant control populations, macular thickness was measured using optical coherence tomography and retinal photographs were graded to assess the severity of retinopathy. Overall, 54 percent of patients had an oxygen desaturation index of ≥10, and 31 percent had an apnea-hypopnea index of ≥15. This SDB prevalence is probably higher than would be expected from the available matched control data. Those with SDB were not sleepier, but they were older and more obese. No significant relationship was identified between the degree of macular thickness and the severity of SDB.
Mason R, West S, Kiire C, Groves D, et al.


Effect of Laser Fragmentation Grids on Phaco Time
In a prospective, randomized trial, doctors from the Center for Vision Science in Bochum, Germany, compared the effect of different fragmentation softening grids in femtosecond laser-assisted cataract surgery on effective phacoemulsification time (EPT) and found that the use of a 350-μm grid led to a significantly lower EPT than the 500-μm grid.

The study evaluated the feasibility of using a femtosecond laser to perform capsulotomy and lens fragmentation in the treatment of patients with senile cataract. Patients were evaluated preoperatively with the Lens Opacities Classification System III (LOCS III). Eighty patients had laser refractive cataract surgery with 350-μm fragmentation grids; 80 additional patients had laser refractive cataract surgery with 500-μm fragmentation grids. Both groups had phacoemulsification using pulsed ultrasound energy, and the EPT was evaluated. 

The mean preoperative LOCS III grade was 3.7 ±0.8 in the 350-μm group and 3.5 ±0.8 in the 500-μm group. The mean laser treatment time was 66.4 ±14.4 seconds in the 350-μm group and 52.8 ±11.9 seconds in the 500-μm grid group. The mean EPT was 0.03 ±0.05 seconds and 0.21 ±0.26 seconds, respectively. 

One of the authors reported a financial disclosure as a member of the medical advisory board for Optimedica Corp. No other author of this study has a financial or proprietary interest in any material or method mentioned.
Conrad-Hengerer I, Hengerer F, Schultz T, Dick B.


Limits of Total Wavefront Laser Vision Correction
Researchers from Spain set out to do a prospective, experimental study of the intrasession and intersession precision of higher-order aberrations measured by the Zywave, a commercial Hartmann-Shack wavefront sensor by Bausch + Lomb, in refractive surgery candidates. They concluded that total ocular aberrations, total HOAs and second-order terms can be measured reliably by Zywave aberrometry without anatomic recognition. Third-order terms and Z40 are repeatable, but not as reproducible, between visits. Fourth-order terms, except for Z40, and fifth-order terms are not sufficiently reliable for clinical decision-making or treatment. 

To analyze intrasession repeatability, one experienced examiner measured 30 healthy eyes five times successively. Excellent intraclass correlation coefficients (ICCs) were obtained for total ocular aberrations, total HOAs and second order terms (ICC, >0.94). The ICCs for third-order terms were also high (>0.87); however, fourth-order ICCs varied from 0.71 to 0.90 (Z40 =0.90). Fifth-order ICCs were less than 0.85.

To study intersession reproducibility, the same clinician obtained measurements from another 30 eyes at the same time of day one week apart. Only total ocular aberrations, total ocular HOAs, second-order terms, Z40, Z31 and Z3_3 had ICCs of 0.90 or more. Bland-Altman analysis showed that the limits of agreement were clinically too wide for most higher-order Zernike terms, especially for the third-order terms (>0.21 μm).

Because the variability of Zywave can be a major limitation of a successful wavefront-guided excimer laser procedure, surgeons should consider treating HOA magnitudes that are more than the intrasession repeatability values (2.77 X SW) as those presented in this study.
López-Miguel A, Maldonado M, Belzunce A, Barrio-Barrio J, et al.


Vision Loss During Treatment A Natural Progression of AMD
Vision loss may occur during ranibizumab treatment and is, in most cases, because of the natural course of age-related macular degeneration.
A retrospective analysis of 290 consecutive eyes comprising cohorts from three clinical settings showed that 21 eyes lost ≥15 letters on the Early Treatment Diabetic Retinopathy Study chart one year after the start of ranibizumab treatment. Fundus images of these eyes were analyzed by two independent readers to investigate the causes of visual loss. A second analysis was performed to compare the baseline characteristics of patients who gained (visual acuity gainers) or lost (visual acuity letters) ≥15 losers.

Among the 290 eyes included, the proportions from each center experiencing visual loss were not significantly different (p=0.2631). Mean visual loss of affected eyes was 27 letters. There was no significant difference between these eyes and others as regards age and gender of patients, laterality, type of choroidal neovascularization, number of visits or initial visual acuity. Visual loss was secondary to the progression of atrophy in eight eyes, fibrosis in five eyes, a combination of fibrosis and atrophy in three eyes, severe subretinal hemorrhage in three eyes and retinal pigment epithelial tear in two eyes. A significant difference between visual acuity gainers and losers was observed for two parameters: age of patients (80.9 ±5.3 years in visual acuity losers versus 77.5 ±7.3 years in visual acuity gainers, p=0.0473) and visual acuity at diagnosis (56.2 ±11.2 versus 49 ±12, p=0.0288).
Cohen S, Oubraham H, Uzzan J, DuBois L, Tadayoni R.


Timolol Effective for Treating Myopic Regression After LASIK
A prospective, randomized, parallel-controlled and double-masked clinical trial from Iran suggests timolol application is effective for treating myopic regression after LASIK, compared with the control group, and that effects last for at least six months after discontinuation.

A total of 102 eyes were evenly and randomly assigned to either Group 1, who received timolol 0.5% eye drops, or Group 2, who received artificial tears. The main outcome measurement of spherical equivalence was limited to patients who attended the final follow-up session six months post-treatment (45 eyes for both groups). 

In Group 1, SE improved from -1.48 ±0.99 D before treatment to -0.88 ±0.91 D six months after treatment, and -0.86 ±0.93 D six months after timolol discontinuation (p<0.001). In Group 2, it was -1.57 ±0.67 D, -1.83 ±0.76 D and -1.91 ±0.70 D, respectively (p<0.001). SE was significantly better in Group 1 six months after treatment and six months after discontinuation of timolol (p<0.001 for both comparisons). There was a 0.26-D decrease in the SE improvement every four months after surgery in Group 1 (p<0.001).
Shojaei A, Eslani M, Vali Y, Mansouri M, et al.