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June 2015

Solar Retina Disease
 Solar Retina Disease 275 183 jometry1
By:

Dr Ling Zhou, Doctor Of Optometrist

Solar retinopathy (also known as, photic retinopathy, foveomacular retinitis, solar retinitis, and eclipse retinopathy) refers to a photochemical toxicity and resultant injury to retinal tissues, usually occurring at the fovea. This entity is commonly associated with sun-gazing or eclipse viewing, and often results in mild-to-moderate visual acuity deficit and/or central or paracentral scotomata. Recovery is spontaneous in nature and occurs over the course of 3-6 months after the inciting event, though visual recovery may be incomplete and patient may suffer from permanent visual acuity deficits and central or paracentral scotomata.

Disease

Solar (or photic) retinopathy refers to a pathophysiologic entity causing       visual disturbance sustained during or after prolonged or high intensity exposure of the foveomacular retinal tissue to light energy.

General Pathology

Histopathalogic analysis of rhesus monkey retinae after prolonged light exposure helped characterize the histopathologic changes observed in solar other photoxic retinopathies. As early as day 2 post-exposure, major changes were observed mainly in and about the retinal pigmented epithelium (RPE). RPE disruption was evident throughout the exposed area, sometimes associated with choroidal damage. Pigmentary changes of the RPE were noted as macrophages were observed engulfing melanosomes in the subretinal space. Resolution of these findings can be seen by 10 days after injury.10

In 1993, ultrastructural pathologic changes of solar retinopathy were explored by Hope-Ross, et al., who had the cooperation of a 65 year-old man scheduled for enucleation for choroidal melanoma. The patient agreed to stare into the sun 6 days prior to enucleation. Findings included photoreceptor changes including vesiculation and fragmentation of photoreceptor lamellae, the presence of whirls within disc membranes, mitochondrial swelling and nuclear pyknosis. Retinal Pigment epithelial cells in the affected area showed plasma membrane changes, smooth endoplasmic reticulum swelling, and changes in lipofuscin granule structure.11

Pathophysiology

The mechanism by which retinal tissue damage occurs in solar retinopathy is photomechanical in nature. Photochemical retinal injury is believed to be a product of free radical formation. Two mechanisms of free radical formation have been proposed. First, absorption of light energy by a molecule causes an electron to enter an “excitation state”, with free radical formation being a means by which such an electron can return to the “ground state” energy level. In returning to the “ground state” energy level, an excited state electron splits a bond within another molecule, forming a free radical.9 Second, light energy absorption can cause excitation of and direct transfer of energy from an intraretinal chromophore – flavoproteins, heme proteins, melanosomes, lipofuscin, and photoreceptors themselves – to oxygen, creating a reactive oxygen species.9 Furthermore, the photochemical injury to the retinal tissues may be thermally enhanced8.

Primary prevention

Prevention of solar retinopathy is in fact the mainstay of therapy. Primary prevention of solar retinopathy includes refraining from direct sun-gazing or eclipse-viewing.

Diagnosis Diagnosis is made based on history and examination findings including physical/biomicroscopic examination of the fundus, as well as diagnostic imaging, such as FA and OCT.

History

Obtaining a good history is important for making a clinical diagnosis of solar or photic retinopathy. Sun-gazing, eclipse-viewing, occupational hazards such as welding without a welding helmet or welding goggles, repeated flash-photography, recent cataract extraction or other ophthalmologic operative procedures may be endorsed by the patient or may require pointed interrogation. Furthermore, cognizance on the part of the ophthalmologist of solar and other astronomical phenomena, such as solar eclipse, may aid in teasing out pertinent history from patients that raise suspicion for solar retinopathy.

Symptoms

Symptoms commonly present within hours of exposure and include blurry vision and central or paracentral blind spot in one, or more commonly, both eyes. Additional complaints may include dyschromatopsia, metamorphopsia, micropsia, frontotemporal headache

Signs Decreased Visual Acuity, usually to a level of 20/25 – 20/100, but possibly worse

Management

Observation only.

Medical therapy

No known beneficial treatment exists for solar retinopathy. Prevention is through education is paramount.

Medical Follow-up

Regular follow-up through the acute phase of disease is at the discretion of the physician.

Prognosis

The bulk of visual acuity improvement has been noted to take place in the first 1 and 6 months after the photoxic event.7, 13,14 Despite more moderate vision loss at presentation, most patients ultimately return to a visual acuity level of 20/20-20/40.7 Improvement has been shown to be achieved earlier and more robustly in patients with visual acuity of 0.2 logMAR (20/30 Snellen visual acuity) at presentation.12 Furthermore, a correlation was found between initial visual acuity and fundoscopic appearance 2 weeks after the phototoxic event.12 Unfortunately, metamorphopsia and central or paracentral scotomata, including those that show some improvement initially, may become permanent.7, 14

eyeglasses Lenses Materials
Eyeglasses Lenses Materials
 Eyeglasses Lenses Materials 1024 683 jometry1
By:
lenses

Plastic lenses, also known as CR-39 lenses

Plastic lenses, also known as CR-39 lenses, are a popular choice for eyeglasses due to their many advantages over other types of lenses. However, they also have some disadvantages that should be considered when selecting eyewear.

Advantages of plastic lenses:

  1. Lightweight: Plastic lenses are lighter than glass lenses, making them more comfortable to wear for extended periods of time.
  2. Impact resistant: Plastic lenses are less likely to shatter or break upon impact than glass lenses, making them a safer choice for sports and other physical activities.
  3. Affordable: Plastic lenses are generally less expensive than other types of lenses, making them a popular choice for those on a budget.
  4. Easy to tint: Plastic lenses can be easily tinted to provide additional protection from the sun or to create a custom look.

Disadvantages of plastic lenses:

  1. Less scratch-resistant: Plastic lenses are more prone to scratches than glass lenses, which can affect their longevity and clarity.
  2. Less clear: Plastic lenses may not be as clear as glass lenses, particularly in higher prescriptions, which can affect visual acuity.
  3. Thicker: Plastic lenses may be thicker than other types of lenses, particularly in higher prescriptions, which can affect the appearance of the eyewear.
  4. Prone to distortion: Plastic lenses may cause more distortion, particularly in wraparound or curved frames, which can affect visual acuity.

In conclusion, plastic lenses offer several advantages over other types of lenses, including affordability, impact resistance, and lightweight. However, they also have some disadvantages, including lower scratch resistance, less clarity, and more distortion. It is important to consider these factors when selecting eyewear and to consult with an eye care professional to determine the best type of lenses for your individual needs and preferences.

Eyeglasses Lenses Material

Trivex lenses

Trivex lenses are a type of lens material that is designed to offer several advantages over other types of lenses. They are a popular choice for eyewear due to their lightweight, impact resistance, and optical clarity. However, they also have some disadvantages that should be considered when selecting eyewear.

Advantages of Trivex lenses:

  1. Impact resistant: Trivex lenses are highly impact-resistant, making them a popular choice for sports and other physical activities.
  2. Lightweight: Trivex lenses are lighter than glass lenses and comparable to polycarbonate lenses, making them more comfortable to wear for extended periods of time.
  3. Optical clarity: Trivex lenses offer excellent optical clarity and are able to correct vision problems such as nearsightedness, farsightedness, and astigmatism.
  4. UV protection: Many Trivex lenses come with built-in UV protection, which helps to protect the eyes from harmful UV rays.

Disadvantages of Trivex lenses:

  1. More expensive: Trivex lenses are generally more expensive than traditional plastic or glass lenses, which can be a drawback for those on a budget.
  2. Prone to distortion: Trivex lenses may cause more distortion, particularly in higher prescriptions or in wraparound or curved frames, which can affect visual acuity.
  3. Less scratch resistant: Trivex lenses may not be as scratch-resistant as other types of lenses, which can affect their longevity and clarity.
  4. Limited availability: Trivex lenses may not be available in all prescriptions or lens styles, which can limit the options for those with specific needs or preferences.

In conclusion, Trivex lenses offer several advantages over other types of lenses, including high impact resistance, lightweight, optical clarity, and built-in UV protection. However, they also have some disadvantages, including higher cost, potential for distortion, less scratch resistance, and limited availability. It is important to consider these factors when selecting eyewear and to consult with an eye care professional to determine the best type of lenses for your individual needs and preferences.

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Polycarbonate lenses

Polycarbonate lenses are a type of plastic lens that are widely used in eyewear due to their many advantages over other types of lenses. However, they also have some disadvantages that should be considered when selecting eyewear.

Advantages of polycarbonate lenses:

  1. Impact resistant: Polycarbonate lenses are highly impact-resistant, making them a popular choice for sports and other physical activities.
  2. Lightweight: Polycarbonate lenses are lighter than glass lenses, making them more comfortable to wear for extended periods of time.
  3. Scratch resistant: Polycarbonate lenses are more scratch-resistant than plastic lenses, making them more durable and long-lasting.
  4. UV protection: Polycarbonate lenses offer 100% UV protection, which helps to protect the eyes from harmful UV rays.

Disadvantages of polycarbonate lenses:

  1. More expensive: Polycarbonate lenses are generally more expensive than plastic lenses, which can be a drawback for those on a budget.
  2. Prone to distortion: Polycarbonate lenses may cause more distortion, particularly in higher prescriptions or in wraparound or curved frames, which can affect visual acuity.
  3. Less clear: Polycarbonate lenses may not be as clear as glass lenses, particularly in higher prescriptions, which can affect visual acuity.
  4. Thicker: Polycarbonate lenses may be thicker than other types of lenses, particularly in higher prescriptions, which can affect the appearance of the eyewear.

In conclusion, polycarbonate lenses offer several advantages over other types of lenses, including high impact resistance, lightweight, scratch resistance, and UV protection. However, they also have some disadvantages, including higher cost, potential for distortion, less clarity, and thickness. It is important to consider these factors when selecting eyewear and to consult with an eye care professional to determine the best type of lenses for your individual needs and preferences.

High index lenses

High index lenses are a type of lens material that is designed to be thinner and lighter than traditional plastic or glass lenses. They offer several advantages over other types of lenses, but they also have some disadvantages that should be considered when selecting eyewear.

Advantages of high index lenses:

  1. Thinner and lighter: High index lenses are significantly thinner and lighter than traditional plastic or glass lenses, making them more comfortable to wear for extended periods of time.
  2. More attractive: High index lenses are thinner and more aesthetically appealing, which can improve the appearance of eyewear.
  3. Better optical quality: High index lenses are designed to provide better optical quality than traditional plastic or glass lenses, resulting in sharper, clearer vision.
  4. UV protection: Many high index lenses come with built-in UV protection, which helps to protect the eyes from harmful UV rays.

Disadvantages of high index lenses:

  1. More expensive: High index lenses are generally more expensive than traditional plastic or glass lenses, which can be a drawback for those on a budget.
  2. Prone to distortion: High index lenses may cause more distortion, particularly in higher prescriptions or in wraparound or curved frames, which can affect visual acuity.
  3. Less impact resistant: High index lenses may be less impact resistant than other types of lenses, which can be a drawback for those who engage in sports or other physical activities.
  4. Limited availability: High index lenses may not be available in all prescriptions or lens styles, which can limit the options for those with specific needs or preferences.

In conclusion, high index lenses offer several advantages over other types of lenses, including thinner and lighter design, improved optical quality, and built-in UV protection. However, they also have some disadvantages, including higher cost, potential for distortion, less impact resistance, and limited availability. It is important to consider these factors when selecting eyewear and to consult with an eye care professional to determine the best type of lenses for your individual needs and preferences.

How to Wear Contact Lenses
 How to Wear Contact Lenses 600 400 jometry1
By:

Nervous? Don’t be. Putting contact lenses in and taking them out is easier than you might think. It may take a few days for your eyes to get used to the feeling of wearing lenses. If you’re having trouble don’t force it, give yourself plenty of time to get comfortable. There’s no rush, you can always try again tomorrow.

Daily Disposable Contact Lenses

Care
Daily disposable contacts are inserted on the eye every morning and thrown away every night, so you don’t need care solutions.

Lifestyle
One and done is an easy care routine for many first-time wearers or people with active lifestyles.

2-Week Contact Lenses

Care
Simply clean daily and store in lens solution overnight to maintain safety and cleanliness.

Lifestyle
2-week contacts require basic care and upkeep, but also enable you to have one pair for a longer period of time than just a day.

Monthly Contact Lenses

Care
Basic care and upkeep—storing and cleaning in lens solution overnight—allows you to keep them for an extended period of time.

Lifestyle
Because you’ll have these longer, they require some amount of responsibility to keep them clean.

 

  • How long will it take for the contacts to feel normal?
    • This varies for everyone. If you feel like it has been too long, the best way to find out why you’re uncomfortable, and what you can do about it, is to talk to your eye doctor.
  • Should the contact move around after I put it in?
    • With proper fitting, contacts should stay in place almost all the time. Even on that rare occasion when a contact lens moves out of place, it usually stays on your eye until you can move it back.
  • Is it okay if my vision is still blurry after putting in my contacts?
    • Many things can adversely affect your vision. It could be as simple as dry eyes, poor-fitting lenses, or an out-of-date prescription. It could also be a sign of a more serious problem not related to your contacts. You should always talk to your eye doctor about any issues you are having with your vision or your contact lenses.
Lenses Material View Optical
Polycarbonate vs. Trivex Eyeglasses
 Polycarbonate vs. Trivex Eyeglasses 450 300 jometry1
By:

When Eye Safty  is a concern, polycarbonate or Trivex lenses usually are the best choice for your eyeglasses, sunglasses and sports eyewear.

Both polycarbonate and Trivex lenses are thinner and lighter than regular plastic lenses. They also offer 100 percent protection from the sun’s harmful UV light and are up to 10 times more impact-resistant than plastic or glass lenses.

This combination of lightweight comfort, UV protection and impact resistance also makes these lenses an excellent choice for children’s glasses and safety glasses.

Polycarbonate Lenses

polycarbonate lenses have become the standard for safety glasses, sports goggles and children’s eyewear. Because they are less likely to fracture than regular plastic lenses, polycarbonate lenses also are a good choice for rimless eyewear designs where the lenses are attached to the frame components with drill mountings.

  • Light weight (Up to 20% lighter and thinner than plastic CR-39)
  • Impact-resistant lenses. (up to 10 times more impact-resistant )
  • UV Protection (100% UV Protection So if you chose Polycarbonate Lenses, don’t pay for UV coating )

Trivex Lenses

  • Thickness. Polycarbonate has a higher index of refraction than Trivex (1.58 vs. 1.53), so polycarbonate lenses are about 10 percent thinner than Trivex lenses.
  • Weight. Trivex has a lower specific gravity than polycarbonate, making Trivex lenses about 10 percent lighter than polycarbonate lenses.Index-Comparison
  • Optical clarity (central). Trivex lenses have less internal stress and may produce sharper central vision than polycarbonate lenses.
  • Optical clarity (peripheral). Trivex lenses have a higher Abbe value and may produce sharper peripheral vision with less chromatic aberration than polycarbonate lenses.
  • Impact resistance. Polycarbonate and Trivex lenses have comparable impact resistance.
  • UV protection. Polycarbonate and Trivex lenses both block 100 percent of the sun’s UV rays without the need for special UV-blocking lens coatings.
  • Availability. Polycarbonate lenses are available in a wider variety of lens designs ( progressive lenses and other multifocals) than Trivex lenses.