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What is the significance of keratometry?

Keratometry (K) is the measurement of corneal curvature, which is used to evaluate the cornea’s power. Astigmatism is caused by differences in power across the cornea (opposite meridians); thus, keratometry quantifies astigmatism. It can be obtained manually or through automated ways using a variety of devices.

Keratometry (K) is the measurement of corneal curvature, which is used to evaluate the cornea’s power. Astigmatism is caused by differences in power across the cornea (opposite meridians); thus, keratometry quantifies astigmatism. It can be obtained manually or through automated ways using a variety of devices. It can be measured in a more finite area of the cornea, such as with a manual keratometer or the IOL Master, or it can be measured in a more sophisticated way, such as with topographers that measure a cornea across a large number of points (Carl Zeiss Meditec). The IOL Master also incorporates K readings and measures axial length as well as other ocular characteristics (such as anterior chamber depth and white-to-white measurements).

Automated vs. manual

Personally, I prefer manual keratometry since it provides a clear insight of the pre-corneal tear film’s integrity as well as a dynamic perspective of the cornea’s surface. You may see the reflections caused by the tear film directly using manual keratometry. You can spot locations where the corneal surface is uneven or compromised. The quality of the measurements will be affected if the tear film is greasy or disturbed, or if the cornea shows mild dystrophy or degeneration (akin to the changes of a pebble tossed into a placid lake). You have a much better idea of the quality and precision of your measurements now.

Acquisition is static with automated measurements. The measurements are taken at a specific point in time and then processed by a computer. As the instrument operator, you have no idea how precise the “measured minute” is.

Because measurement errors are matched 1:1 to refractive results, keratometry is an essential measurement in cataract surgery. You’ll get a 1.00 D refractive surprise if your K measurements are off by 1.00 D. If your K is off, you’ll have an unpleasant refractive surprise after surgery. A refractive miss result is exceedingly frustrating to both the doctor and the patient in current generation of cataract surgery with premium intraocular lenses (IOLs). In cataract postoperative patients, residual ammetropia may necessitate a second surgical treatment, such as IOL exchange, piggybacking of an extra IOL, or a surface procedure.

If you have any doubts about your K readings, repeat them on another day. If there is any hint of a problem or if the measurement is difficult to get, we will repeat K readings. I usually measure the right eye first, then the left, and then double-check.

If I’m not happy with any part of my measurement—for example, if the patient has dry eye disease or is using contact lenses—I’ll have them return after receiving dry eye therapy and not wearing contact lenses for 1 to 3 weeks, depending on the lens type. It’s possible that the first K measurement you took isn’t the one you’ll need during surgery. It’s the first thing you should do before infusing drops, doing gonioscopy, or doing anything else that can affect the corneal surface if you’re getting ready for cataract surgery.

Although manual K is simple to master, it does require some practice to ensure precise measurements. Before you write down your findings on a piece of paper, you must be confident in your measurements. Only doctors, including residents, will perform keratometry for patients undergoing cataract surgery at Omni Eye Surgery.

For their surgeries, some surgeons prefer the most up-to-date automated K. Because each approach evaluates various parts of the cornea, it’s a good idea to compare manual and automated measurements to obtain a better sense. You should also expect a match between the measured corneal cylinder and the patient’s spectacles.

The significance of a correct reading

It’s critical to take care of the corneal surface before undergoing ocular surgery. Patients are occasionally referred for cataract surgery; nevertheless, the fundamental concern is the corneal surface, not the cataract. Patients who had their corneal surface repaired have opted out of cataract surgery in some circumstances since the issue was more about the bad corneal surface than the cataract. During keratometric measures, clinical signs can be picked up that can assist you identify more mild cornea deterioration, such as basement membrane dystrophy, that is more difficult to detect and easy to neglect with a slit lamp examination. Patients with corneal dystrophy should be informed that, while their vision will improve following cataract surgery, they will still have a corneal issue that could impact their post-operative vision.

If an operator is having trouble generating a measurement, try to figure out why right away. Dry eye, a damaged cornea, meibomian gland dysfunction, corneal illness, or even poor patient positioning or fixation during testing could all be contributing factors.

It is critical to have a strong understanding of keratometry. With those measurements in your hands, the surgeon is putting the surgical result of the patient in your hands. It is your responsibility to ensure that they are clean and to raise a red signal if they are not.

Keratometric readings are also important when fitting contact lenses, especially gas permeable lenses, to monitor corneal disease and detect keratoconus. Keratometry is frequently used to identify keratocones.

Keratoconus

Keratoconus is a corneal degenerative condition that causes abnormal and irregular steepening (and irregular astigmatism) of the cornea, resulting in decreased vision, scarring, and the possibility of corneal perforation. Occasionally, a patient will present with unexplained visual loss until the technician gets K measurements. Then we discover that the cornea is completely aberrant, resulting in blurred vision. Corneal crosslinking, gas permeable contact lenses, Intacs (embedded stromal rings), and penetrating keratoplasty are among treatment possibilities for keratoconus (corneal transplant).

If the K readings are beyond of what is considered a normal range, or if the mires are irregular, you are immediately alerted to the possibility of keratoconus pathology. With corneal crosslinking, the sooner we detect it, the sooner we can stop corneal steepening from progressing.

Some practitioners favor automatic keratometry, while others prefer manual keratometry. The most essential aspect is that we may obtain these measures in a variety of ways. They should all make sense and be connected. If the measurements differ significantly, they should be retaken and examined to rule out other pathology.

Text by: Gabriel Guzman

Since prehistorical times the human eye have evolved to become what we now can describe as a hybridized optical design. Let’s explain this further. When our eye fixates on an object of interest, it never stands still for a long time. In fact, it engages in a fast push-pull movement in order to provide the best focused image of the intended target. And this is when we start talking about single vision lenses.

Unlike our ancestors, we now prioritize a sharp central vision that is combined with motion-sensitive side vision, wherein our eye reacts to changes in light and movement and also where the single vision lenses come to the field.

As its name says, when we talk about single vision lenses we are referred to a lens that has one focal length so they have one prescription for the whole piece, and they are normally destined to people under 40 who are either short-sighted (myopic) or long-sighted (hyperopic) and used for general purpose, as they are more likely to have just one type of visual requirement.

So, for example, if you couldn’t see the TV from the sofa or the table that is on the other side on the living room, you’d probably need a pair of glasses with a single-vision prescription so you could see your favorite TV program properly.

But what happens when we surpass the age of 40? When our eyes start to lose their ability to focus near objects (known as presbyopia), single-vision glasses can be used to help with reading and some close-up tasks. Nevertheless, there are other problems that they are able to correct, such as:

• Double vision
• Glares or halos around bright lights
• Headaches
• Eye fatigue
• Eye soreness

What are the benefits of wearing single vision lenses?

Nowadays, we can count of one of the best material in the market, called MR™ which allows you to have not only a thinner and more fashionable pair of glasses, but you can also feel relieved of any fear of caring heavy weight over your nose, due to its low specific weight. But what about that common thought of accidentally letting your glasses fall down? Never mind! They have a high resistance to impact.

Beyond restoring your ability to see clearly, there are other plenty of benefits of wearing single vision lenses:

• This type of lenses may boost the quality of your life with improved visual health and acuity.
• Single vision lenses can help relieve you of eye strain and ensuing fatigue and migraines.
• Like all types of eyeglass lenses, they can help you protect your eyes from impact, trauma and common irritants like dust, sand and insects.

Nowadays everyone is being reminded of how important it is to have good eye health and, in this field, a vision eye test is becoming a more common way to look after our visual health..

More than 50 per cent of sight loss could be prevented, so getting your eyes tested is now the homework that we have to do in order to help prevent, or limit, the damage caused by certain eye conditions. We all can do this at home, following these steps and check our entire family’s vision, but remember: this is not a substitute for a complete medical exam by a licenced optometrist.

Why are regular eye examinations important?

● Having your vision corrected can improve the quality of your day-to-day life.
● They will also help detect certain eye conditions such as cataracts, glaucoma and age-related macular degeneration, which could lead you to sight loss in the short time.
● Poor vision could be a risk factor for falls.
● Vision eye tests for children are also vital to make sure that any visual problems such as squint, lazy eye (amblyopia) or short-sightedness (myopia) are detected and treated.

What would happen if we don’t apply for an eye vision test on time?

Did you know that many people first learn that the have really serious eye health conditions such as diabetes, high blood pressure, high cholesterol and even cancer from – yes, you guessed it – an eye vision test?

And it’s because our eyes have been called throughout the time as “the window to our soul”. But, what does it mean? It turns out, they also are often a very effective window to our overall health.

The main reason why is because during an appropriate eye vision test, your doctor can get to know the health and condition of your eye and prevent the development of several diseases such as myopia, which is becoming epidemic, and glaucoma.

Of all serious eye diseases, glaucoma is probably the sneakiest. That’s because there are no discernable symptoms in most cases of early glaucoma — nothing to alert you that something’s going wrong.

And now, are you ready to save the date for an eye vision test, on time?

Just For Eye Care Professionals (ECPs)

This is where the TCP-1 tabletop refraction system comes into action. In difficult times where social distancing and saving spaces are the hot topics, this equipment is a precision optical instrument for accurate subjective refraction.

The TCP-1 provides different charts such as a regular chart (E chart, C chart, Number chart and children chart); a polarized chart that have all turned to red-green chart; a reg-green balance and red-green polarized chart that can be adjusted to fit reg-green lenses of the Phoropter.

What about saving space? In times of taking care of our health, distance is very important for us, that’s why the TCP-1 is the most space-saving refraction unit for convenient use that comes with a infrared, WIFI and bluetooth remote control that will help you with a more avant-garde experience. But the best part of it is its compact appearance and sophisticated design due to its phoropter that lifts up and down automatically, improving by this your professional eye testing feeling and value.

Interview with Mariano Portillo, General Manager at LATAM OPTICAL LLC

According to an official report released by the United Nations (UN) every one in four inhabitants of Latin America will be over 60 years old by 2050 and, having said this, there will be more people with visual diseases related to aging. In fact, countries such as Brazil, Chile, Colombia and Costa Rica currently have more than 30% of their population over that age, a situation that already occurs in the Nordic countries and Japan.

In this context, we spoke with Mariano Portillo, General Manager at LATAM OPTICAL LLC, a company that provides Ophthalmic Lenses in 22 countries in Latin America, the Caribbean and the United States, to help us understand his vision about this scenario that threatens our visual health.

What is the main problem that you currently observe in this segment of the population?

As a connoisseur of the industry, I realize that there is a focus on the millennial population, which is the main our main consumer, as it is also a group that recently joined us and that does not need a properly correction, but what they really need is prevention against the consequences of not addressing the problem in the right time.

Three-in-ten U.S. adults say they are ‘almost constantly’ online. As smartphones and other internet-connected devices have become more widespread, 31% of U.S. adults now report that they go online “almost constantly,” up from 21% in 2015, according to a new Pew Research Center survey conducted Jan. 25 to Feb. 8, 2021.

Overall, 85% of Americans say they go online on a daily basis. That figure includes the 31% who report going online almost constantly, as well as 48% who say they go online several times a day and 6% who go online about once a day. Some 8% go online several times a week or less often, while 7% of adults say they do not use the internet at all.

How we did this

Adults under the age of 50 are at the vanguard of the constantly connected: 44% of 18- to 49-year-olds say they go online almost constantly. By comparison, just 22% of those ages 50 to 64 and even smaller shares of those 65 and older (8%) say they use the internet at this frequency.

While the share of 18- to 29-year-old who say they use the internet almost constantly has risen 9 percentage points since 2018, it remains unchanged since 2019. Meanwhile, the share of constantly online Americans ages 30 to 49 has risen 14 points since 2015, and the share of 50- to 64-year-olds has risen from 12% in 2015 to 22% in 2021. The share of Americans ages 65 and older saying this has not grown since the Center began asking this question in 2015.

Other demographic groups that report almost always going online include college-educated adults, adults who live in higher-income households and urban residents.
Some 42% of adults with a college degree or more education go online almost constantly, compared with 23% of adults with a high school diploma or less education. At the same time, the shares of White, Black and Hispanic adults who report using the internet almost constantly are statistically the same. Some 37% of Black adults say this, while 36% of Hispanic adults and 28% of White adults report going online on an almost-constant basis. The share of Hispanic adults who are almost always online has risen 17 points since 2015, while there has been no growth for White and Black adults during this time period.

While 40% of adults with an annual household income of $75,000 or more say they use the internet almost constantly, this is true for just 27% of those living in households earning less than $30,000 a year. Adults who live in urban areas are the most likely to say they go online almost constantly, compared with suburban residents and an even smaller share of those who live in rural areas.

CORRECTION (March 2021): A previous version of this post incorrectly listed partisan affiliation as a way in which the survey is weighted to be representative of the U.S. population. None of the study findings or conclusions are affected.

Note: This is an update of a post originally published on Dec. 8, 2015, and later updated on July 25, 2019, by Andrew Perrin and Madhu Kumar. Here are the questions used for this report, along with responses, and its methodology.

Andrew Perrin and Sara Atske “About three-in-ten U.S adults say they are ‘almost constantly’ online, March 26th, 2021, accessed April, 5th, 2021, https://www.pewresearch.org/fact-tank/2021/03/26/about-three-in-ten-u-s-adults-say-they-are-almost-constantly-online/

Non-visible 420nm, Yellow 450nm, Orange 527nm and Red 600nm

We may introduce in this specific order those ophthalmic filters that once were used exclusively for treating vision problems such as low vision and now it is being increasingly considered due to the visual stress caused by hyperconnectivity (enhanced by the pandemic) or futuristic therapies such as Biohacking.

Let´s take as a starting point the very first day of existence. According to book of Genesis in the Bible, God said: “Let there be light”, and there was light. Having said this, we should know that those first beams of light came together with its entire high-energy-blue component.

Millions (or thousands) of years later, scientists Akasaki, Amano and Nakamura were awarded with the Nobel Prize 2014 in Physics, after performing their studies and testing the application of light diodes, LED.
Starting in the early 1990s, white light technologies -with its high blue light component- gradually replaced most light sources, including displays and screens of every digital device that we use in our daily on-line activities.

LED technology contributes to conserving the Earth’s resources, as well as providing an affordable source of light for millions around the world BUT this technology come with a dark side: human brain cannot discern between day and night, between light and darkness.

How does the blue light affect us?

There are three main issues caused by direct exposure to digital devices or other sources of blue light; these effects have an impact on the body in general and particularly on the visual system.

1. Refraction and perception. It is the range of the visible spectrum with highest refractive index, which is why to the emmetropic eye, they refract before reaching the retina causing focus, dispersion and contrasting issues.
2. Photo-toxic effects on the retina. Perhaps this is the most controversial point due to the lack of tests on humans, although the results obtained in animal tests (rodents) have confirmed its negative consequences.
3. Circadian rhythm. When the sun sets, it is precisely the absence of blue light what activates the secretion of melatonin which allows our body to start the sleep cycle. The abrupt change from incandescent to LED lighting in all its forms, increased by overexposure to digital devices is causing Health authorities to worry because of their negative impact on sleeping patterns and those repairing tasks that our body perform while we sleep.

This issue was approached by the optical industry in the past.

As early as 1938, B&L offered their Ray Ban “shooting glasses” with yellow lenses that highlighted the importance of cutting off blue light to improve vision on cloudy days, driving in foggy weather, shooting practice and night vision.

Turquoise-blue light is beneficial… only in daytime.

As we mentioned before, the rise of LED light with a high component of blue light in public lighting, mobile devices, and all type of screens, would be confusing our brain by delaying the melatonin secretion.
Although we know that just as the blue-violet light would be the most damaging one to the vision system and turquoise light is the one we need to remain active during the day, the fact that we keep on receiving this kind of light during night hours might be counterproductive.

Today, lenses are being offered according to their spectral cut-off to use at different times of the day to reduce the impact of blue light on the circadian cycle:

• 420 cut-off filters: this is the most demanded technology in recent years and showed a notorious increase during the pandemic. They filter all harmful blue violets up to 420nm; therefore, they also guarantee a 100% UV cut. They are also clear hence they do not alter color perception and can be always used and in all areas.
• 450 cut-off filters (yellow): These types of lenses guarantee a cut-off of blues up to 450nm. They allow the pass of turquoise blues but affect our color perception.
• 527 cut filters (orange): they guarantee a total cut of blues in all ranges. Regarding the circadian rhythm, it is recommended for after sunset only, since the blue color during the day is necessary to keep us active. These were the first filters to be considered by the science community when sleeping problems and screens in our lives became a subject of study.
• 600 cut-off filters (red): some alternative therapies support them as a way of removing all traces of blue and even green colors during the last night hours to keep the pineal gland up and running. But those who ever worked with filters and know how a 600 filter works, know that, besides some pathologies or some cases of extreme photophobia, this filter and its low transmissibility makes it not very suitable to our vision system.

In conclusion, for those ECP’s involved in low vision and / or safety filters, the acquisition of these types of filters are essential and to the optical industry in general to assure its continuous supply.