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| Vol. 22, #40 • Monday, October 18, 2021 |
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Off the Cuff: In Front of Our Eyes
The more you know, the more you realize how little you know. I suspect that this frustrating paradox is fairly universal among those who focus on things long and hard enough to actually begin to understand them.
At the risk of you thinking I have become neurotic or that I am losing my mind, I will admit that I think about the anterior surface of the eye a lot. Even though I know I will never fully understand it, I try to make sense of what is an impossibly complex system. I figure the more I understand, the better I will be at fixing it when it breaks.
I am slowly but surely making progress. When I started down this path eight years ago when we opened our office, what I knew about dry eye was a small drop in a vast ocean. What I know today can at least fill a bucket. Certainly not a lot of knowledge in the overall scheme of things, but at least I am able to grasp the enormity of what there is to know.
For example, we know the cornea has more nerves than any other tissue in the body. Why are there so many? They didn’t end up there by accident and there are far too many for simple sensation or pain. What are all these nerves doing?
This year’s Nobel Prize for physiology or medicine was awarded to Americans David Julius and Ardem Patapoutian who figured out how cells in the skin detect temperature and touch. You are probably thinking the same thing I did: how did we not already understand something so basic and rudimentary? Well, we didn’t. Julius and Patapoutian deciphered the genetic coding, molecular basis and biomechanics of how we sense cold and pressure. Their breakthrough opened the door to how we sense a variety of stimuli both internal and external.
With increased focus on homeostasis and its importance in ocular surface function, the biggest missing puzzle pieces lie on the receptor side. What is being measured? Where is it being measured, and how are these control signals processed? Moreover, how do they affect function? It would make sense that all of those corneal nerves are doing something—likely a lot more than we can possibly understand today. I suspect that we will soon discover that some of the greatest secrets of the body lie hidden right in front of our eyes.
Want to share your perspective?
Write to Dr. Epstein at artepstein@optometricphysician.com.
The views expressed in this editorial are solely those of the author and do not necessarily represent the opinions of Jobson Medical Information LLC (JMI), or any other entities or individuals.
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Benzalkonium Chloride-preserved Anti-glaucomatous Eye Drops and Their Effect on Human Conjunctival Goblet Cells In Vitro
Most intraocular pressure (IOP)-lowering eye drops are preserved with benzalkonium chloride (BAK). This can increase side effects and decrease adherence. Particularly, damage to the mucin-producing conjunctival goblet cells may be an issue due to instability of the tear film. Researchers aimed to investigate the effect of IOP-lowering eye drops preserved with BAK on cultured human conjunctival goblet cells. Eye drops Brimonidine Tartrate Teva (BT) with 0.005% BAK, Dorzolamide Stada (DS) with 0.0075% BAK, Optimol (OP) with 0.01% BAK, and Latanoprost Teva (LT) with 0.02% BAK were included. Human primary cultured goblet cell survival was evaluated using a lactate dehydrogenase assay on human goblet cells after treatment for 30 minutes and 6 hours with the different anti-glaucoma drug formulations.
All eye drops examined, except BT, reduced goblet cell survival. The impact of eye drops on goblet cell viability was correlated with the time of exposure as well as to the concentration of BAK. After 30 minutes of exposure, cell viability was 93% for BT (0.005% BAK; p=0.93), 71% for DS (0.0075% BAK; p=0.067), 70% for OP (0.01% BAK; p=0.054), and 69% for LT (0.02% BAK; p=0.022), and exposure for 6 hours reduced cell survival to 74% for BT (p=0.217), 52% for DS (p=0.011), 34% for OP (p=0.017), and 31% for LT (p=0.0007).
LT, OP and DS reduced human goblet cell survival in a time-dependent manner. BT did not affect goblet cell survival. Cell survival was correlated with the BAK concentration in the eye, drops making 0.02% BAK-preserved LT most toxic and 0.005% BAK-preserved BT least toxic. Researchers concluded, based on the study, decreasing BAK in eye drops for chronic use seemed important to reduce damage to the goblet cells. However, they added, future studies would be needed to further explore this finding.
SOURCE: Hedengran A, Begun X, Müllertz O, et al. Benzalkonium chloride-preserved anti-glaucomatous eye drops and their effect on human conjunctival goblet cells in vitro. Biomed Hub. 2021; Aug 13;6(2):69-75.
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Long-term Effect of Early Phacoemulsification in Primary Angle Closure Glaucoma Patients with Cataract: A 10-Year Follow-Up Study
This study assessed the 10-year effects of early phacoemulsification with intraocular lens (IOL) implantation in primary angle-closure glaucoma (PACG) patients with cataract. This prospective cohort study included 102 eyes of 102 patients with PACG. All patients had coexisting cataracts compromising vision. Patients underwent phacoemulsification and foldable IOL implantation. The main outcome measures were anterior chamber depth (ACD), angle width, value of intraocular pressure (IOP), and number of medications needed postoperatively and during follow-up.
Half (53%) of the patients were female, with ages ranging from 55 to 73 with a mean of 59.82 ±5.19 years. Mean IOP decreased significantly from 22.15±2.08 mmHg at baseline to 14.08±2.13 mmHg postoperatively (p˂ 0.05). The ACD increased from 2.2±0.21 preoperatively to 3.73±0.25 postoperatively (p˂0.001). Nasal angle width increased postoperatively to 40.05±2.09 compared to the preoperative value of 16.02±2.08 (p˂0.001). Temporal angle width increased from 13.05±2.07 to 41.9600±1.94 (p˂0.001). Anti-glaucoma treatment significantly decreased postoperatively (p˂0.001). A significant positive correlation was detected between ACD and angle width, while a negative correlation was detected between IOP and both ACD and angle width (p˂0.001). There was also a significant negative correlation between postoperative angle width and IOP (p˂0.001). Preoperative lens thickness was positively correlated with preoperative IOP and number of medications, while it was negatively correlated with preoperative AC depth and angle width. Preoperative lens thickness positively correlated with postoperative IOP and medications. Complete and qualified success was achieved in 69.65% and 30.4% of cases, respectively, while 2.9% failed to be controlled. Visual acuity significantly improved from 0.17±0.1 to 0.9±0.08 (p˂0.001). All parameters showed high stability throughout the follow-up period.
Investigators wrote that phacoemulsification with IOL implantation was a safe and effective early modality for long-term control of IOP in PACG patients with coexisting cataract. They added that the effects can persist for at least 10 years.
SOURCE: Helmy H. Long-term effect of early phacoemulsification in primary angle closure glaucoma patients with cataract: a 10-year follow-up study. Clin Ophthalmol. 2021; Sep 29;15:3969-81.
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Quantitative Analysis of Early Diabetic Retinopathy Based on Optical Coherence Tomography Angiography Biological Image
With the development of the economy and improvements in living standards, the incidence of diabetes mellitus (DM) and diabetic retinopathy (DR), which is a complication of DM, are on the rise. Researchers analyzed early DR in patients with macular zone changes in biological images using optical coherence tomography angiography. A prospective case study was performed on 59 participants: 35 healthy eyes (control group), 35 eyes with diabetes but no DR group (no DR group), and 35 eyes with mild DR (NPDR group). All quantitative comparisons of parameters, including the fovea vascularity area, circularity index and vascular complexity parameters, were performed using a biological image analysis software.
The foveal avascular zone (FAZ) area, FAZ circularity index, number of branches in the area, and the total of the single branches' length in the area were 0.366 ± 0.031, 0.834 ± 0.037, 3241.8 ± 268.3 and 3.860 × 107 ± 0.194 × 107; and 0.421 ± 0.030, 0.739 ± 0.023, 2956.6 ± 476.4 and 3.177 × 107 ± 0.161 × 107 in the no DR group and the NPDR group, respectively, which was significantly different from the corresponding parameters of the control group (p<0.05). Moreover, there were significant differences between these two groups (p<0.05).
The study showed that early microcirculation changes in the macular area of the retina is associated with disease progression. Researchers noted that early changes in DR can be analyzed using optical coherence tomography angiography.
SOURCE: Shi Y, Lin PY, Ruan YM, et al. Quantitative analysis of early diabetic retinopathy based on optical coherence tomography angiography biological image. World J Clin Cases. 2021 Sep 6;9(25):7365-71.
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Industry News
J&J Survey: Early Eye Health Intervention an Obstacle Despite Fear of Blindness
Globally, 70 percent of adults don’t plan to get their eyes examined this year, despite acknowledging the critical importance of eye health, according to a Johnson & Johnson Vision Global Eye Health Survey announced in conjunction with World Sight Day on October 14. The global survey found 86 percent of adults fear losing their sight above any other sense. While 88 percent of respondents view eye health maintenance a priority for their overall health, only 52 percent reported getting annual eye exams. Read more.
X-Cel Specialty Contacts Launches Educational Program Featuring REMLens
X-Cel Specialty Contacts launched “Feed Your Mind,” an educational program featuring the recently launched REMLens for overnight orthokeratology. The program offers four courses and enables individuals to book a virtual staff training session or an in-person training & fitting session on a date and time that is convenient for the practice. Learn more.
Prevent Blindness Joins in World Sight Day
Prevent Blindness participated in World Sight Day October 14 by providing the public with steps to care for their and others’ eyesight. World Sight Day is an international day of awareness, held annually on the second Thursday of October to focus attention on the global issue of eye health. Coordinated by the International Agency for the Prevention of Blindness, this year’s theme was “Love Your Eyes.” Read more.
AAOF Announces Student Giving Matching Travel Grant Recipients
The American Academy of Optometry Foundation announced the recipients of the 2021 AAOF Student Giving Matching Travel Grants. View the receipients.
Danelli Ocular Creations Releases MYBOClean System
Danelli Ocular Creations announced the release of its first products, the MYBOClean Daily Eyelid Cleansing Brush and the MYBOClean Hydrating Lids and Lash Cleansing Gel. Learn more.
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