The Lash Picture Show : Twenty lashes for ECPs who overlook this problem

Gene linked to Dry Macular Degeneration

High prevalence of cataracts continues

The Lash Picture Show : Twenty lashes for ECPs who overlook this problem

Miss Amelia, a retired elementary teacher, was capable, spritely and 82 years of age. She was in my exam chair complaining of an intermittent blur when looking up at traffic lights. “I’m so discouraged,” she said, “I just got these new glasses from another doctor and that’s when the trouble started. When I look up at traffic signals they are blurred. It isn’t always there, but it keeps coming back and it has me scared.”

“Did you go back and tell him you were having trouble,” I asked, knowing full well that the doctor she had seen was a highly competent professional and a missed pathological finding was a remote possibility.

“I called him and he said to bring the glasses in so he could check them again. I did that, but he said the prescription was exactly right, so I came to you to see if you could figure out what was wrong.”

I took the old eyewear, her written Rx and her new eyewear to our in-office lab and soon concluded that the change in prescription seemed reasonable and the written Rx had been correctly filled. The new prescription was “better in everyway,” as she put it, except for looking up at traffic signals. I had her view a fixation light in the six cardinal directions and although there was no blur at first, she
suddenly commented that when the light was up and centered her vision got blurry. The riddle was solved! She had a small area of mascara smudges on the upper central area of each lens. We were able to explain the problem and adjust the frame sufficiently for her lashes to clear the flatter curve of her new lenses.

Lash Relief

 
Optical instruments are designed so that there is a comfortable distance from the eye of the viewer when the instrument is in use. This distance is termed the “lash relief” by optical instrument designers. It can be a factor in choosing your next binoculars, telescope or lensometer (see sidebar, “Getting the Best View”). Lash relief is also needed when spectacle lenses are fitted. It’s an easy-to-overlook part of good eyewear design.

Patients who have problems with lash relief tend to have certain things in common. It should be no surprise that a short vertex distance is often a factor, but other predisposing causes include lashes that are unusually long, either naturally or otherwise, frame wrap, facial anatomy, lens design (asphericity or base curve), position of the lens bevel (on minus lenses), lens material, lens prescription and cold weather.

Cold Weather

In cold, dry weather organic (plastic) lenses tend to build and maintain a static electricity charge that can be sensed when the lashes brush close to the back of the lenses without actually contacting the lens’ surfaces. If you have ever experienced this, you know how annoying it can be. This is most likely to happen with new lenses for several reasons: 1. patients are more diligent about cleaning new lenses so there is a greater static charge, 2. new lenses have relatively pristine, oil-free surfaces contributing to building a greater static charge, and 3. patients are much more aware of each and every attribute of new eyewear until the newness wears off. In most cases, the annoying sensation caused by static electricity slowly decreases as the lenses are worn. This is probably due to a reduction in the static build-up as the lens surfaces become coated with oils from the skin. If the lashes are just shy of touching the lens surfaces, the frames can usually be realigned to give a bit more lash relief and the problem will be solved.

A more difficult situation is the one in which the lashes actually make contact with the lenses. Younger patients can usually tell you their lashes are touching. Elderly patients may not feel the lashes lightly contacting the lenses, but they may complain of difficulty in keeping their lenses clean. A simple diagnostic test consists of cleaning the lenses, having the patient blink a few times with the eyewear in place and then looking for smudges that are usually located centrally and slightly below center. The best way to avoid lash relief problems is to predict them in advance and head them off at the pass, as the saying goes.

Questions For The Ladies

 “Did you curl your lashes today?” “Do you always curl your lashes?” “Do you ever use anything to thicken and lengthen your
lashes?” “Have you ever had problems with your lashes touching or smearing your lenses?” If you anticipate a lash relief problem, it’s best to tell the patient in advance that this may present a design issue. You may even want to tell them you have several alternatives to avoid the problem, each of which have some benefits and some draw backs.

The Alternatives

• Increase the eye size. This increases the sag depth and gives a slightly greater vertex distance. The increase must not unduly increase the weight or be undesirable from a cosmetic standpoint. Increasing the eyesize works best for lenses with steeper curvatures. For a lens with a plano posterior curve there is no advantage to increasing the eye size, yet for a lens with a -6.00D posterior curve the increase in lash relief can be significant.

• Decrease the bridge size. This can work well with the “increased eye size” solution because it offsets the overall increase
in the width of the eyewire. For fixed-bridge frames it will also tend to increase the vertex distance. Be sure that the bearing area and appearance will be acceptable with a narrower bridge.

• Adjust the frame’s vertical positioning so that the MRPs fall at about the point at which the lashes are most extended. It’s important to remember that the greatest cornea-to-back-of-the-the-lens distance will almost always fall at the MRP level unless the patient has a prism prescription.

• Select a frame with minimal wrap. Frames with a strong wrap place the lenses closer to the eyes.
 

• Request your lab to give you special bevel positioning for patients with minus lenses. Labs sometimes call this a 1/3-2/3 bevel because the apex of the bevel is positioned about 1/3 of the way back from the front surface of the lenses. This moves the back surface of the lens away from the eye. 

• Ask the lab to give you lenses with base curves that are steeper than recommended by the lens manufacturer. Be aware that this will increase peripheral aberrations and will decrease the performance of the lenses. Your patient should be cautioned about this also. This alternative is especially undesirable if the patient’s Rx is not close to the next steeper base curve on the manufacturer’s recommended curve chart. You should also recognize that steepening the base curve has very limited value for small diameter lenses. See Fig. 1.

• Lash relief problems can be created by using lenses with flatter curvatures, so you should use caution when going to higher-index lenses. For minus lenses there is not only a flattening of the curvature, but there is also thinner edge that limits the amount you can move the bevel.

Occam’s Razor
The principal of Occam’s Razor, that the simplest solution (e.g. picking one alternative) is the best solution, does not strictly apply when solving lash relief problems. Using a combination of the above alternatives, each in moderation according to your patient’s needs, will usually give the most acceptable result.

If All Else Fails
Because using a longer vertex distance can dramatically narrow the reading area and the corridor width of PALs and also because of other limitations related to the patient’s anatomy or prescription, it is sometime impossible to give adequate lash relief. In such cases patients can be offered the alternative of curling or cutting their lashes...or they might wish to consider contact lenses.

By Palmer R. Cook, Od

Source: 20/20 Magazine, Jobson Medical Information LLC. Published here under license."

Gene linked to Dry Macular Degeneration

Scientists from the United States and China have identified the first gene directly associated with the onset of severe "dry" macular degeneration, one of two forms of age-related macular degeneration that currently threatens the vision of up to nine million older Americans.

The discovery, based on work with both human and mice cells, centers on a specific immune system protein called TLR3. Although helpful in fending off illness when confronted with certain viral infections, this molecule, when routinely activated, was also found to raise the risk for "dry" macular degeneration by attacking infected retinal cells.

But, the study authors also found a genetic silver lining in the form of a mutated version of TLR3 -- a so-called "inactive" or "less active" TLR3 -- that suppresses this retinal death process, seemingly protecting people from the eye disease.

"This represents a major step forward in our understanding of the dry form of macular degeneration," said study co-author Dr. Kang Zhang, a professor of ophthalmology and human genetics at the Shiley Eye Center at the University of California, San Diego, School of Medicine. "And with the identification of this potential target, we can try to develop treatments for a disease which, for the moment, we can't treat."

But celebration over isolating TLR3's role in dry age-related macular degeneration (AMD) has been tempered by some potentially troubling implications that the new findings seem to have for a cutting-edge investigational treatment recently unveiled to target the so-called "wet" form of AMD.

The treatment in question, known as "RNA interference," or RNAi, works by "silencing" genes that bring about wet AMD. Unfortunately, the treatment appears to simultaneously activate TLR3 -- resulting in a 60 percent spike in retinal cell death among mice and humans genetically susceptible to developing dry AMD. The result: RNAi may help protect against wet AMD while boosting the risk for dry AMD, the study authors said.

"This raises particular concerns regarding RNAi therapy for wet AMD," Zhang said. "But by establishing this link between the treatment for the wet form of AMD and the potential harmful effect on the dry form of the disease, we can perhaps better understand the mechanisms of both diseases."

Age-related macular degeneration is the leading cause of blindness in adults over the age of 60, according to the U.S. National Eye Institute. The progressively worsening disease affects the macula portion of the eye, located in the center of the retina, which enables detailed vision.

The disease can strike in two ways: wet and dry. In its wet form --sometimes referred to as "advanced AMD" -- loss of vision occurs rapidly due to the growth of abnormal blood vessels under the macula, leading to leakage of blood and fluids. In its more slowly progressing dry form, light-sensitive macular cells begin to break down, leading to a blurring of vision in one or both eyes, according to the eye institute.

Addressing the new findings, Rando Allikmets, a professor of ophthalmology, pathology and cell biology at Columbia University, urged restraint.

"I think these results have to be taken with caution, because the association effect of TLR3 with AMD is very small when compared to the disease's association with some other genes," he said. "And there has been already one study saying there is absolutely no association of the TLR3 genetic variant with AMD. So, this raises a question and a need for further edification. It could be that this is just a spurious finding, and there is, in fact, no association with AMD."

By HealthDay

By Matt Hasson, Katrina Altersitz. Ocular Surgery News India Edition September 2008

In India, nearly 74% of adults 60 years and older have cataracts or have undergone cataract surgery, according to a population-based study. Women have a significantly higher prevalence than men, and nuclear cataract is the most common type.

Age-related macular degeneration, however, was shown to be rare, a finding that may be partly attributed to India’s relatively short life expectancy.

The INDEYE Study, conducted in Delhi to represent northern India and Pondicherry to represent southern India, detailed the rates and risks of cataract and AMD.

G.V.S. Murthy, MBBS, MD, MSc, and other members of the research team presented preliminary study results at this year’s All India Ophthalmological Society conference in Bangalore.

In interviews with Ocular Surgery News, Dr. Murthy and fellow investigators Astrid E. Fletcher, PhD, Ravilla D. Ravindran, MD, and Badrinath Talwar, MD, discussed the prevalence of cataracts and AMD, and examined risk factors for cataracts.

Dr. Fletcher served as the principal investigator, with Drs. Murthy and Ravindran leading the investigation in Delhi and Pondicherry, respectively. Dr. Talwar assisted in the clinical examinations in Pondicherry.

Dr. Fletcher recalled investigators’ dismay upon encountering the high incidence of cataract amid ongoing initiatives to stem the disease.

“Despite all the efforts of the national program for the control of blindness in India, which have made a huge impact in many ways, our study, which was in the older population, the over 60s, still showed a high proportion of untreated cataracts,” she said.

Dr. Fletcher suggested that there may be insurmountable barriers in patients’ access to cataract surgery.

“It isn’t the cost of the surgery that is so much the problem, it may be other factors such as the costs of family members to accompany somebody to the hospital,” she said.

Study design and protocols

The INDEYE Study was conducted between 2004 and 2006. After administering a questionnaire, investigators selected 3,072 patients (1,460 men and 1,612 women) in Delhi and 3,257 patients (1,512 men and 1,745 women) in Pondicherry, Dr. Murthy said.

Patients underwent a clinical examination, anthropometry, visual acuity measurement, digital imaging of cortical and posterior sub capsular opacities, photography of nuclear opacities and fundus photography of the retina, macula and disc, Dr. Ravindran said.

The questionnaire was used to collect demographic and environmental data. Patients also gave blood samples that were tested for antioxidant levels.

Objectives and protocols for the INDEYE Study were tested in the Feasibility Study, a 2003 pilot survey conducted in a rural area of Haryana.

Before embarking on the INDEYE Study, investigators increased the target population age from 50 years, as used in the feasibility study, to 60 years and older, Dr. Murthy said.

Age and gender

The overall prevalence of cataract — including operated cataract — in those older than 60 years was 73.6% (75.2 % in Delhi and 72% in Pondicherry), Dr. Murthy said. Among patients older than 70 years, 81% of men and 85.8% of women in Delhi, and 61.2% of men and 68.5% of women in Pondicherry had fairly advanced nuclear cataracts, the study showed.

“Three out of every four individuals [aged older than 60 years] in this country do have a cataract,” Dr. Murthy said at the meeting. “That is the challenge. We know cataracts exist. We know cataract surgery rates are increasing in this country. We also know that significant proportions are still untreated.”

Among those 70 years and older, 11.8% of men and 13.9% of women in Delhi, and 14.7% of men and 18.2% of women in Pondicherry had cortical cataract. Also, 33.7% of men and 42% of women in Delhi, and 26.1% of men and 34.4% of women in Pondicherry had posterior sub capsular cataracts, he said.

Overall, women had a higher risk of having any cataract type, he said, attributing the disparity to women formerly having less access to cataract surgery than men.

“We find that as age increases, both among the men and women, both at the northern site as well as the southern site, you find that there is an increase in the prevalence of nuclear cataract,” he told OSN. “We know that the people whose eyes we couldn’t grade tended to be the older people who got the most severe opacities.”

Dense cataracts hindered imaging of lenticular opacities and retinal structures.

“That is a problem, which means that lens opacities are still a major problem in India,” Dr. Murthy said, adding that the number of fundus images that could not be graded increased with age.

Risk factors for cataracts

The study found that cooking fuel, midday sun, tobacco use and low levels of vitamin C were associated with a higher risk of cataracts.

“The one thing that had a very strong correlation in the study was the exposure to cooking fuel,” Dr. Ravindran said. “We looked in the South at the association of cataract with cooking fuel, and there’s a strong correlation of people having cataract if they’re using unclean fuel. The risk to the patient is about 1.8 times compared to using only clean fuel, like using only kerosene stoves or liquefied petroleum gas.”

Patients in Delhi had a 1.02 times higher risk from using unclean fuels. Also, residents of Pondicherry who always used unclean fuels had a 3.18 times higher risk of cataract, compared with a 1.41 times higher risk in Delhi.

Midday exposure to sunlight also proved to be a risk factor, they found.

The type and duration of tobacco use also played a role. For example, residents of Pondicherry who used tobacco at any time in their lives had a 1.63 times higher risk of cataract, compared with a 1.31 higher risk in Delhi. Tobacco chewing was more common in Pondicherry (35%), while bidis were more prevalent in Delhi (48%).

In Pondicherry, tobacco chewing elevated the risk of cataract 1.67 times. Bidis increased the risk of cataract in Delhi 1.3 times. Past hookah use also increased the risk of cataract in Delhi by 1.46, according to the study.

Dr. Fletcher said there is a link between cataracts and blood levels of antioxidants, particularly vitamin C.

“I’m struck by the fact that this older population in India has … low levels of vitamin C and what the implication is for the health,” she said. “Ophthalmologists tend to think of the eye, but there are all of these other important factors that relate to not just vitamin C and its relationship to the eye but also vitamin C and its possible effects on general health.”

Prevalence of AMD

Dr. Talwar discussed the significance of low AMD rates in the study and the difficulty in grading eyes for AMD because of the high prevalence of dense cataracts, which hampered photography of the fundus.

“The prevalence of late stage AMD is so low that we can’t really say for sure whether there was any kind of associated risk factor,” he said.

Dr. Fletcher said the current rate of late-stage AMD in the INDEYE population is 0.9%, or 1.1% to 1.2%, based on the number of eyes that could be graded. Eyes that could not be graded because of dense cataracts or corneal opacities were not included. The macula could not be graded in 27% of eyes.

Dr. Murthy partly attributed the low incidence of AMD to India’s short average life expectancy.

“To actually have AMD as a major problem, you have to live much longer than people, in general, live in India,” he said. “The proportion of the population over 70 is miniscule right now. Once the life expectancy increases, then obviously AMD would become a major problem.”

However, focusing on an age-specific portion of the population, not the entire population, gives a more reliable assessment of AMD rates, Dr. Fletcher said.

“I agree that we wouldn’t have had as many people over 80 as we would have in comparable Western populations, but as long as you’re quoting age-specific rates, it should be like for like,” she said.