A
weekly e-journal by Art Epstein, OD, FAAO
Volume 10, Number 36 |
Monday, September 13, 2010 |
As many of you know, for the last few years, I have been living in Phoenix and shuttling back and forth to
New York to see patients. At first I returned every other week, then every third week. Eventually, it became once a month
and then the visits became even less frequent. The problem was that I loved my practice and my patients, but the commute
and being away from home, in addition to my other travels, became increasingly difficult.
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Impact of Gender and Iris Color on Dark-Adapted Pupil Diameter | ||||
Researchers sought to assess the utility of digital color sensing to quantify iris color using digital photographs and to determine whether
gender or iris color affects the dark-adapted pupil diameter (DAPD). They found that contrary to long-held beliefs, female patients and
blue-eyed patients do not have larger DAPD.
They measured the right DAPD of subjects aged 18–80 years (n=263) with no eye disease after 2 minutes of dark adaptation at 1 lux using the NeurOptics pupillometer. They also took a high-resolution digital slip lamp photograph of the iris and subjectively classified iris color as blue, blue-green, green-brown, light brown or dark brown. The researchers also objectively measured the digital photographs on-screen with the Minolta TV Color Analyzer II using the Commission Internationale de l'Eclairage system of color description and performed regression analyses to identify correlations between subjective iris color, Commission Internationale de l'Eclairage measurements and DAPD. According to the researchers, gender and iris color had no effect on the DAPD. They observed that the Minolta TV Color Analyzer could discriminate all blue eyes (blue and blue-green) from all brown eyes (light and dark), but could not distinguish between shades of blue or shades of brown. They also noted that green-brown irises had no unique chromatic properties and could not be distinguished from other colors using their technique of digital color analysis. The study researchers concluded that digital color sensing is a useful technique for objectively describing iris color. |
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SOURCE: Bradley JC, Bently KC, Mughal AI, et al. The effect of gender and iris color on the dark-adapted pupil diameter. J Ocul Pharmacol Ther 2010; 26(4):335-340. |
IOP Measurement Using a CL-Embedded Sensor | ||||
To evaluate a novel contact lens-embedded pressure sensor for continuous measurement of intraocular pressure
(IOP), repeated measurements of IOP and ocular pulse amplitude (OPA) were recroded in 12 eyes of 12 subjects in sitting and supine
positions using three configurations of the dynamic contour tonometer: slit-lamp mounted (DCT), hand-held (HH) and contact lens-embedded
sensor (CL). The IOP and OPA for each condition were compared using repeated measures ANOVA and the 95% limits of agreement
were calculated.
It was reported that the sitting IOP (mean and 95% CI) for each configuration was DCT: 16.3 mmHg (15.6 to 17.1 mmHg), HH: 16.6 mmHg (15.6 to 17.6 mmHg) and CL: 15.7 mmHg (15 to 16.3 mmHg). The sitting OPA for each configuration was noted as DCT: 2.4 mmHg (2.1 to 2.6 mmHg), HH: 2.4 mmHg (2.1 to 2.7 mmHg) and CL: 2.1 mmHg (1.8 to 2.3 mmHg). Supine IOP and OPA measurements with the CL and HH sensors were both noted to be greater than their corresponding sitting measurements, but were significantly less with the CL sensor than the HH sensor. The mean difference and 95% Limits of Agreement were smallest for the DCT and CL sensor comparisons (0.7 ± 3.9 mmHg) and widest for the CL and HH sensors (–1.9 ± 7.25 mmHg); these wider limits were attributed to greater HH measurement variability. It was concluded that the CL sensor was comparable to HH and DCT sensors with sitting subjects and is a viable method for measuring IOP and OPA. Moreover, supine measurements of IOP and OPA were greater than sitting conditions and were comparatively lower with the CL sensor. Additionally, HH measurements were more variable than CL measurements and this influenced the Limits of Agreement for both sitting and supine conditions. |
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SOURCE: Twa MD, Roberts CJ, Karol HJ, et al. Evaluation of a contact lens-embedded sensor for intraocular pressure measurement. J Glaucoma 2010;19(6):382-390. |
Dark Adaptation in Type 2 Diabetes During Transient Hyperglycemia | ||||
The authors of the following study sought to examine dark adaptation in subjects with type 2 diabetes during
transient hyperglycemia. They randomized 24 subjects with type 2 diabetes and minimal diabetic retinopathy to undergo an oral
glucose tolerance test (OGTT) or to remain fasting.
The study authors measured dark adaptometry in one eye, chosen at random, using a computer-controlled dark adaptometer and dark adaptation as well as capillary blood glucose at baseline and 80 minutes into the OGTT/fasting test. They reported that blood glucose remained stable throughout the examination in the 12 fasting subjects, whereas glycemia increased in the 12 OGTT subjects, from 8.6 ± 2.1 at baseline to 21.1 ± 3.6 mM after 80 min. In the OGTT group, four out of seven subjects with delayed dark adaptation at baseline reached normal values during hyperglycemia. According to the authors, all examined aspects of rod adaptation were accelerated by hyperglycemia (time to rod-cone break –26%; time to rod intercept –16%, rod sensitivity recovery slope (log units/min) +35%), whereas no measurable change in cone adaptation was seen. The results are consistent with rod adaptation being limited by glycemia and with rod adaptation being delayed in subjects with diabetes compared to healthy subjects, the delay being reversible in response to hyperglycemia. |
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SOURCE: Holfort SK, Jackson GR, Larsen M. Dark adaptation during transient hyperglycemia in type 2 diabetes. Exp Eye Res 2010;Aug 21 [Epub ahead of print]. |
News & Notes | ||
NEXT UP: PHASE 3 STUDY OF CAN-FITE'S DRY EYE DRUG. Can-Fite BioPharma Ltd. has opened an Investigational New Drug application (IND) with the FDA for a Phase 3 study of its lead drug, CF101, in patients with moderate to severe dry eye syndrome. CF101 was found to be safe and well tolerated in an earlier Phase 2 study, in which the drug was taken orally as a monotherapy for 12 weeks. (Because a statistically significant benefit in the clearing of fluorescein staining in the nasal, temporal, papillary and inferior parts of the cornea were documented in the Phase 2 study, the company has initiated a Phase 2 clinical study [currently ongoing] with CF101 in patients with glaucoma.) According to Can-Fite, the randomized, double-masked, Phase 3 trial, which will enroll approximately 240 patients at multiple centers, will compare 2 doses of CF101 to placebo. The patients will be treated for 24 weeks and the main outcome assessments are improvement of corneal fluorescein staining, tear production and dry eye symptom score. | ||
BAUSCH + LOMB LAUNCHES NEW
ALAWAY TV AD CAMPAIGN, WELCOMES NEW EXEC. Bausch + Lomb
has launched its advertising campaign for Alaway, the 12-hour eye itch relief drops. Television ads are currently airing across major
U.S. broadcast and cable networks. The campaign, which targets allergy sufferers, uses the slogan, “It's not just your allergies,
it's your eyes” and will run through September.
In other company news, Daniel M. Wechsler has been named as corporate vice president and global president of Bausch + Lomb's Pharmaceuticals business, assuming Pharmaceuticals responsibility from Brent Saunders, B+L CEO, who has been acting as interim global president of the business unit for the past several months. Mr. Wechsler was most recently head of U.S. Strategy, Commercial Model Innovation and Business Development for Merck & Co. |
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