How Ortho-K Controls Myopia Progression?

Orthokeratology, commonly known as Ortho-K, is a specially designed rigid gas permeable contact lens that is worn overnight. The lenses gently reshape the cornea, temporarily eliminate your refractive error so that there is no need for glasses or contact lenses during the day.

Blue-lit eye and contact lenses for vision correction.

How does Ortho-K Correct Myopia? 

Myopia (nearsightedness) happens when light focuses in front of the retina. Ortho-K is designed to flatten the cornea in order to focus the light on the retina. The following diagram shows how Ortho-K work:

Ortho-K lens effect on cornea before, during, and after wear.

How does Ortho-K Control Myopia Progression? 

Close-up of Ortho-K lens on eye under fluorescein light.

When light focuses in front of the retina, this blurriness can send a signal to the brain that the eye is too short and needs to grow longer to bring distant objects into clearer focus, and hence myopia progresses. 

Ortho-K’s unique design creates a central area of focus (where the visual correction occurs) while causing peripheral defocus in a way that is opposite from the usual defocus seen in myopia, slowing down the elongation of eyeball.

Diagram of central focus and peripheral defocus in Ortho-K.    Comparison of single vision vs. Ortho-K correction for myopia.

What are the Benefits of Ortho-K? 

  1. Reduce progression of myopia: Studies suggest that Ortho-K may play a role in slowing the progression of myopia in children and adolescents.
  2. Non-surgical: Ortho-K provides a non-surgical alternative to procedures like LASIK, SMILE pro, TransPRK and ICL.
  3. Freedom from daytime correction: People who wear Ortho-K lenses can experience clear vision throughout the day without relying on glasses or contact lenses.
  4. Safe and effective: Ortho-K is safe if correct lens wearing and cleaning is practiced.

Who is an Ideal Candidate for Ortho-K? 

Ortho-K is broadly applicable and well-suited for a variety of conditions, providing significant relief and positive outcomes for many individuals. For example:

  • Children and adolescents
  • Adults with active lifestyle
  • Athletes
  • Alternative approaches to refractive surgery
  • Myopia
  • Astigmatism

What You Can Expect from Ortho-K

Patients who start using Ortho-K lenses often see results fairly quickly. While it may take up to two weeks or more to reach full vision correction, some people experience noticeable improvement in just a few days.

If you’re nearsighted and want to find out if you’re a good candidate for Ortho-K, schedule a contact lens fitting with OasisEye Specialists to explore the best options for achieving sharp, clear vision while safeguarding your eye health for years to come.

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Why is my vision blurry?

vision blurry

Understanding your vision is the first step in improving it!

Most people deal with some amount and form of unclear vision. From nearsightedness to farsightedness, astigmatism to old age, everyone’s eyes and clarity of vision are different. The more you know about what causes blurry, unclear vision, the better decisions you can make to care for and improve your vision.

By 2050, according to a new report from the Brien Holden Vision Institute in Australia, almost half the world will be nearsighted and require some form of corrective lens, up from a quarter of the global population in 2000.

There are three main factors that can affect your eyes and create blurry, unclear vision:

  1. Genetics. These are the eye factors you were born with. Does your family have a history of glasses or cataracts? More than likely, you will experience something similar during your life. Learn about your family vision history so you can know what might be part of your vision future, and ask your eye doctor for a detailed exam of your eye structure so you can understand what’s naturally affecting your vision.

    Smiling elderly couple sitting on a couch, looking at a smartphone together in a bright, comfortable living room.

  2. Lifestyle choices and experiences. Choices you make and things that happen to your eyes throughout life can affect your vision in many ways. Behaviours like smoking can slowly harm your vision over many years, while accidents like an eye injury during sports can lead to unclear vision and additional vision conditions as you get older. On the other hand, positive nutrition choices and wearing sunglasses can help protect your vision.

    A hand crushing a pack of cigarettes, symbolising quitting smoking and promoting healthier lifestyle choices.

  3. Natural aging. Regardless of your genetics and life experiences, the fact remains that as you get older, the eye also ages and begins to lose some of its flexibility, which creates less clear vision. This is called presbyopia, and nearly every person will experience some degree of blurry vision due to it after the age of 50.
Happy elderly woman wearing glasses, smiling outdoors in a park, showcasing clear vision and positive ageing.

Now for the good news! Even though almost everybody experiences some form of blurry or unclear vision in their lives, our practice and surgeons offer a complete program of proven solutions that can benefit nearly every patient, giving you more options than ever before to achieve better, fuller vision.

Have questions about your vision? Give us a call! We’re happy to help answer your questions.

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How exercise affects your eyes

Regular exercise has long been recognized as a way to improve overall health and well-being. Exercise can reduce the risk of heart disease, stroke and obesity, among other ailments. However, what many people do not realise is that exercise can also have a positive impact on our eyes.

Studies have shown that regular exercise can reduce the risk of developing serious eye diseases that may lead to blindness. These diseases include diabetic retinopathy, glaucoma and macular degeneration, which are often linked to high cholesterol level, diabetes and high blood pressure. By reducing these risk factors, exercise can help preserve vision for a longer period.

While no direct correlation has been found between exercise and glaucoma, research has shown that intraocular pressure is reduced after exercising. This is due to the acceleration of aqueous outflow, leading to lower intraocular pressure than usual. People who regularly exercise have a lower risk of developing glaucoma than those who do not. According to the American Academy of Ophthalmology, people who engage in moderate physical exercise are 25% less likely to develop glaucoma than those who are mostly inactive. However, caution should be exercised as certain positions and postures can exacerbate glaucoma, such as a head-stand.

Age-related macular degeneration is a leading cause of severe vision loss worldwide in people over the age of 60. Although there is no direct link between exercise and macular degeneration, studies suggest that exercise can reduce the risk of developing the disease. This is because exercise can improve blood flow to the retina, which is essential for maintaining healthy vision.

In addition to reducing the risk of eye diseases, exercise can also improve energy levels, lower blood pressure and aid in weight loss. All these factors contribute to improved overall health and well-being. Regular exercise can promote a healthier lifestyle, leading to better rest for the body and improved quality of life.

In conclusion, exercise is beneficial not only for the body but also for the eyes. Regular exercise can significantly lower the risk of developing serious eye diseases. While exercise cannot single-handedly prevent or cure eye diseases, it can certainly help in your overall well-being. Additionally, it is crucial to get regular eye checks, as they can aid in the early detection of any eye disease. Don’t forget to visit our centre, OasisEye Specialists, where we provide comprehensive eye care services to help you maintain optimal eyesight.

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Men vs Women: Eye Health and Vision

It might come off astounding at how contrasting vision and eye health could be between men and women.
Take for example, men tend to succumb in sustaining sight-threatening eye injuries than women, however, women do tend to be more at risk to various eye diseases. What could both sexes do to address such eye concerns?

Common Eye Diseases in Women

Women are more susceptible to glaucoma and age-related macular degeneration (AMD) than men. The progressive loss of central vision is known as AMD, whereas, damage to the optic nerve would result in permanent vision loss known as glaucoma. Women are more susceptible to these diseases due to having longer life expectancies than men. Annual routine eye exams are beneficial for early detection hence, the best way to prevail them.
Besides the diseases mentioned above, women are also more prone to chronic dry eyes and basic refractive errors. When dry eyes are left as it is, it may lead up to an increased risk of eye infections. Symptoms of dry eyes include redness, discomfort, prickly sensations, irritation, and blurred vision.

Risk Factors for Eye Diseases

Age is a major risk factor in eye disease developments. However, for women this too includes pregnancy, birth control, as well as menopause. This is because it involves significant changes and fluctuations in hormone levels. Dry eyes is more anticipated due to these hormone changes too. Birth control may show indications of a woman’s chances in cataract development.

Eyes of Men and Hormones

In adolescence, pubescent boys may turn out nearsighted (myopic) for a short period of time as their eyes develop. As they undergo a growth spurt, their eyes may get longer. It should be noted that oftentimes this effect lasts into adulthood. Despite that, it can be simply resolved with spectacles or contact lenses. They may also consider refractive surgery such as TransPRK, ICL, etc. once they reach adulthood and their refraction stabilises.

Eye Injuries in Men

Comparatively to women, men are more susceptible to eye injuries as they are oftentimes more exposed to work in hazardous occupations or partake in high-risk sports. Men are also less inclined to wear protective eyewear and this facilitates the risk more when compared to women. Men too often tend to tough out their injuries and seek professional advice only after the injuries are intolerable. Whereas, women would have been more emotionally driven by the pain and anxiety to seek for advice sooner.

Vision in Men and Women

Both men and women actually see things differently. When it comes to distinguishing subtle differences in colour, women are better than men at it. Men in actuality are more commonly susceptible to colour blindness which are inherited from their mothers. In retrospect, men surpass women at identifying minute details and rapid movement. So don’t blame men too much if they can’t tell your lipstick shades apart!
One theory to account for these differences is that they go back to the hunter-gatherer days, Men did the hunting while women did the foraging, so the men would have needed to spot game at a distance in order to be effective hunters, whereas women needed to be able to tell nutritious plants apart from poisonous ones (especially green and yellow tones).

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What Is Nystagmus?

Nystagmus is an eye condition where the eyes move rapidly and are unable to control. The areas of the brain that control eye movements are not working properly. There are three types of movement of nystagmus which are horizontal nystagmus (moving from side to side), vertical nystagmus (moving up and down), rotary nystagmus which move in a circular motion. This eye condition usually happens in both eyes and can occur in children or adults. The speed of movement may vary, it can be fast or slow and shake more in a certain direction. Therefore, you may have noticed nystagmus patients will tilt or turn their head to see clearer. This is because it helps to slow down the eye movements.

Types of nystagmus : Congenital and acquired.

Congenital nystagmus

Congenital nystagmus normally occurs in infants at the age of 6 weeks to 3 months old. It likely affects both eyes by moving horizontally (side by side). Congenital nystagmus causes are yet unknown, but sometimes it might be due to inheritance.

Acquired nystagmus

Acquired nystagmus usually occurs later in life. It can be caused by serious medical conditions, drugs or alcohol consumption.
Generally, children with nystagmus don’t feel their eyes shaking but notice some blur of vision. Unlike adults with nystagmus will often feel shaky when looking around.

Cause of nystagmus

In some cases the cause of nystagmus is still unknown. In other cases, nystagmus can be caused by other eye conditions.
Possible nystagmus causes :

  • Family history of nystagmus
  • Albinism
  • Certain eye disorders in infants or children (etc. congenital cataracts and binocular anomalies such as strabismus)
  • Multiple sclerosis
  • Inner ear problems (etc. Meniere’s disease)
  • Trauma or head injury (common happens in younger people)
  • Stroke (common happens in older people)
  • Alcohol or drug consumption
  • Use of certain medications (etc. lithium or anti-seizure medications)

Symptom of nystagmus

The main symptom of nystagmus is that eyes move rapidly and are unable to control. The movement usually is side to side. It also can be up and down or circular motion. The speed of movement can vary fast or slow and shake more in a certain direction.

In addition, other nystagmus symptoms may include:

  • Dizziness
  • Photophobia (sensitive to light)
  • Having difficulty seeing in dark environment
  • Blur of vision
  • Turned or tilted head position to see
  • Shaking environment

Nystagmus Treatment

Nystagmus are treated based on the underlying causes. Those who are born with nystagmus usually are not able to be cured. However, refractive correction with glasses or contact lenses is able to provide them a clearer vision which may help slow down the rapid movement.

Surgery repositioning the eye muscles that move the eyes is rarely done, and it does not correct or cure nystagmus. It only helps people with nystagmus to keep their head in a more comfortable position by limiting eye movement.

In acquired nystagmus sometimes it can go away by treating the underlying causes of nystagmus. For instance by treating the medical condition or stopping drug or alcohol intake.

Nystagmus can be diagnosed by an ophthalmologist. The ophthalmologist will examine the eyes to rule out any eye condition which relates to nystagmus conditions including binocular anomalies, cataract and any retina disease including optic nerve. Sometimes they also refer to an ear examination ,a neurological examination and brain imaging (computerised tomography (CT) and magnetic resonance imaging (MRI)) if necessary to rule out the underlying causes.

Therefore, it is advisable to visit an ophthalmologist as soon as possible if you notice any unusual sign or symptom of nystagmus especially for parents with infants or children. In addition, an eye screening can also be beneficial.

Close-up of a person with vertical nystagmus, showing uncontrolled vertical eye movements depicted with directional arrows

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The impact of smoking on eyesight

Smoking your way to blindness

Tobacco smoking is the consumption of tobacco which can be found in lighting cigarettes, cigars and pipes. The practice of inhaling and exhaling such fumes poses an epidemic on its own, known most commonly to cause significant damage to the heart and lung. Ever thought how smoking could develop or exacerbate eye problems that are sight-threatening and potentially lead to blindness? Some of the eye diseases are such as:

Dry Eye Syndrome

Tobacco smoke irritates the conjunctival mucosa of the eye, decreases the quantity and quality of tears, thereby causing eye dryness. The insufficiency of quality tears causes smokers to experience itchiness, eye redness, foreign body sensation, swelling, and watery eyes.

Cataract

It is the clouding of the crystalline lens of the eye. Studies have found smokers significantly increase their risk of cataract development up to 3 folds as the practice of smoking causes alteration in the cells and increases build-up of heavy metal residue in the crystalline lens.

Age Related Macular Degeneration (AMD)

AMD is an acquired degenerative condition that impairs the central vision. Smoking causes constriction of the blood vessels and reduction in the level of lutein and zeaxanthin in the macula, which accelerates the rate of developing AMD by up to 4 times. It causes one to have difficulty in reading, seeing fine details, poor facial recognition, seeing wavy lines, and many more.

Uveitis

It is the inflammation of the central layer of the eye, known as the uvea. According to studies, smokers have an increased risk of 2.2 times to develop uveitis compared to non-smokers.

Glaucoma

Glaucoma is an eye disorder which is indicated by compromised blood flow to the optic nerve, resulting in progressive loss of nerve tissue and gradual vision loss. Smoking contributes to this condition by increasing plaque formation in the blood vessels, which in turn reduces blood flow.

Diabetes Retinopathy

It is established that smokers with Type 1 diabetes mellitus (DM) have a higher risk of developing diabetic retinopathy. The act of smoking combined with the chronic hyperglycemic state damages the tiny blood vessels in the retina by reducing retinal blood flow, causing these vessels to break, leak or even block. Not only do smokers significantly increase their risk for all these diseases, it affects the eyes of people around them via passive exposure (secondhand smoke) as well. The negative impact of smoking during pregnancy can be transmitted to newborns, contributing to higher risk of visual disorders. Residents within Klang Valley in areas such as Cheras, Puchong, Shah Alam, Petaling Jaya, and Kepong can visit our low vision specialist, Ms Vinodhini Naidu to have their eyes examined at Nexus Bangsar South KL branch. Residents in Seremban 2, Senawang, Sendayan and Port Dickson can visit Dr Teh Wee Min at our Seremban branch. Residents in Johor Bahru, Skudai, Kulai, Iskandar Puteri, Senai, Tebrau, Batu Pahat, Kluang, Segamat can visit Dr Ling Kiet Phang or Dr Chan Choon Teng at our Johor Bahru branch. Residents in Perai, Bukit Mertajam, Butterworth, Penang island, Alor Setar, Kulim and Sungai Petani can visit Dato’ Dr Haslina at our Penang branch.

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Contact Lenses

A contact lens is a transparent piece of “plastic” that sits on the front surface of the eye. It can provide access to clear vision, in addition to having various therapeutic usages. Like the idea of Cinderella being fitted with the perfect pair of glass slippers, finding the right pair of contact lenses is essential to ensure comfort throughout the duration of wear. How do we address this?

Before purchasing a pair of contact lenses, one should get their eyes checked with an eyecare professional, such as an ophthalmologist, optometrist or an optician with a Contact Lens licence. A thorough eye examination, which includes understanding your lifestyle, purpose of wear, vision and prescription check, and suitability of wear, is crucial to evaluate your suitability of wearing contact lenses. Contact lenses are great for improving your cosmetic appearance, flexibility of being glasses-free and useful for sports activities in which glasses are a hindrance.

Contact lenses are not a one-size-fits-all. The ideal best fit needs to be assessed for optimal fit and comfort. When a contact lens is fitted loosely, the lens might drop out or you may feel immediate discomfort upon insertion. Conversely, a tight contact lens may feel comfortable initially but become uncomfortable and cause eye redness after a few hours.

Contact lenses are available in a variety of lens wearing schedules, also known as modality. It refers to how long the contact lens can be worn after it is removed from its packaging and how soon it should be disposed or replaced. Replacement schedules could be daily, biweekly, monthly, 3 monthly, 6 monthly or yearly. As an example, daily disposable contact lenses should be discarded after a single day of wear and would be great for occasional wearers and perfect for a day out.

Do you know that there are various contact lens materials in the market? Depending on the material, the contact lenses may be soft, rigid or a hybrid of both. Examples of materials are hydrogel, silicone hydrogel, rigid gas permeable and many more. Each material has its own pros and cons, and therefore should be chosen based on your purpose of wear, desired duration of wear, refraction and ocular condition.

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Prosthetic Eye

An ocularist’s main duties are to create a prosthetic by moulding, colour matching and supplying the prosthetic to enable the patient some form of symmetry to the facial area. The aim of an ocularist is to replace the affected area cosmetically with the best symmetry possible. Ocularist try to create comfort for the patient, with as much movement as they possibly can of the prosthesis.

Close-up of a person holding a prosthetic eye, demonstrating the realistic appearance of ocular prostheses.

Eye plays a very important role in facial expressions. Ocular prosthesis rehabilitation can produce a significant impact for an individual’s physical, physiological, social and psychosomatic health for those who have a missing eyeball or loss of any tissue or organ. The reason for losing an eye can be due to the result of congenital defect, disorder, accidental trauma, serious ocular diseases, or surgical intervention. Surgical procedures for the removal of the eye can be classified as evisceration and enucleation. After the surgical procedure, the following treatment includes implant retained or a custom made acrylic ocular prosthesis.

A prosthetic eye can help to improve the appearance of the individual who has lost an eye. Wearing an eye patch or bandage is also one of the choices for individuals yet if the entire eye is removed, ocular implant and prosthesis prevent the eye socket’s tissues from growing into the empty space. A custom made ocular prosthesis is preferred as it provides close adaptation to the tissue surfaces and provides maximum comfort.

Prosthetic eye is commonly called or known as “glass eye” or “fake eye”. It acts as a shell that covers the structures of the eye socket. It does not restore vision so the vision will still have no perception of light (NLP).

What Is a Prosthetic Eye Made of?

Skilled professional crafting a custom prosthetic eye with precision tools, highlighting the detailed process of ocular prosthesis creation.

“What is a prosthetic eye made of?” is a frequently asked question. A prosthetic eye can be made up of a few materials that can adapt with the eye socket tissue closely, such as hard, plastic acrylic. The common material used is acrylic plastic polymer which is also known as polymethyl methacrylate (PMMA). PMMA is lightweight, shatter-resistant and is an alternative to glass where glass was used at the beginning of this technology. Silicone polymers also used to make artificial eyes.

How is an ocular prosthesis created?

Before and after images of a patient with and without a prosthetic eye, showing the cosmetic improvement and symmetry achieved through ocular prosthesis.

Prosthetic eye can be created when the eye socket is ready and stable after the surgery, approximately 3-6 weeks after the surgery. Prosthetic eye must be created by an ocularist who specialises in custom-crafting artificial eyes. There is a layer of the eye known as sclera, which is seen as the white of the eye. During the evisceration surgery, the damaged eye’s internal organs are removed while leaving the sclera intact. Inside the sclera is then placed an implant where it adds volume to the bony socket. Once the implant is put in place, the other layer of the eye is stitched. The eyelid needs to be closed together then a stitch is put in place for a week for 10 days. After 3-6 weeks of the surgery, the process of placing an artificial eye begins. The ocularist will measure the amount of space in between the eyelids and create a prosthetic shell. This is then hand painted such as it matches the colour of the normal eyes.

Adjustments and refitting of the prosthetic eye is needed as time goes on due to the fact that the eye socket can change in shape over time. Prosthetic eyes require yearly polishing by an ocularist and replacement every 5 to 7 years.

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Low Vision Aids (Near)

Low vision aids are designed to improve visual performance and provide enrichment of daily experiences. Just like distance low vision aids, near low vision aids can be optical, non-optical and electronic devices.

Usually children tend to not complain about having difficulty with their near tasks due to their strong accommodation. However, when school activities increase and get more sophisticated with smaller reading material, greater magnification is required and objects need to be brought closer, making reading more fatiguing. Near aids can be beneficial when this becomes an issue for them.

Near Low Vision Aids:

Magnifying Spectacles

Magnifying spectacles enhancing text clarity, providing hands-free vision aid for individuals with low vision.

Advantages
– Hands free
– Larger field-of-view
– Prolonged reading can be done
– Binocular or Monocular depending on the individual’s need
– Portable
– Cosmetic appearance

Disadvantages
– Higher power, higher working distance
– Illumination will be obstructed (going closer will block the illumination)
– Close reading distance causes fatigue and uncomfortable posture
– Not effective for individuals with constricted visual fields
– Individual with eccentric fixation are unable to fixate through the spectacles

Hand magnifier with or without illumination

Hand magnifiers with and without illumination used for reading small text, beneficial for individuals with visual impairments.

Advantages
– Convenient for short-term tasks
– Can use at comfortable reading distance
– Individuals with constricted visual field can benefit
– Available in both illumination and non-illumination

Disadvantages
– User unable to read and write simultaneously
– Maintaining focus is difficult
– Individual with tremors may not be able to hold it properly
– Visual field is limited

Stand Magnifier

Various stand magnifiers used for prolonged reading and writing, providing support for individuals with shaky hands or arthritis.

Advantages
– Suitable for prolonged reading
– Beneficial for individual with shaky hands (tremors, arthritis)
– Available in both illumination and non-illumination.

Disadvantages
– Field of view reduced
– Bulky
– Posture affected
– Difficult to use if the surface is not flat

Solid Lenses Magnifier

Solid lens magnifiers placed on reading materials, offering low magnification for extended reading tasks.

Advantages
– Prolonged task can be done

Disadvantages
– Only available in low magnification
– Heavy

Visual Field Enhancement Devices:

Eccentric viewing Technique

Eccentric viewing training chart used to help patients improve their peripheral vision by adjusting their fixation points.

A technique which can greatly improve a patient’s ability to determine objects and faces when a person views it peripherally with another area of visual field.

Different types of visual field enhancement devices including field expanders, Fresnel prisms, and mirror reflecting systems for individuals with peripheral vision loss.

Non-Optical Devices

Typoscope – used as a guide for reading and writing for a person with a large visual field defect.

Typoscope aids for reading and writing, helping individuals with visual field defects to focus on specific text lines.

Extra Illumination – Different types of illumination needed varies for each individual and depends on their diagnosis and extent of pathology. High illumination required for most of the low vision patients. Direct lighting is useful for most of the patients and usually is advisable to place it 45 degrees with the visual axis for the better seeing eye.

Various_illumination_aids_such_as_clip-on_lights,_table_lamps,_and_high_beam_torchlights_to_enhance_visibility_for_low_vision_individuals.

Increase image size and print

Large print assistive tools including keyboard stickers, books, labels, and measuring cups to help individuals with low vision.

Talking Devices

Talking assistive devices including a watch, scale, and calculator that provide audible outputs for visually impaired individuals.

Electronic devices – Include closed-circuit televisions (CCTV), video magnifier systems, large print computer programmer and screen reader software such as JAWS and MAGic. With the advancement of technologies, electronic devices could benefit moderate to severe visual impaired individuals which normal optical aids or non-optical aids do not benefit them. The only drawback of electronic devices was most of the devices were expensive.

CCTV magnifier, portable CCTV, JAWS screen reader, and MAGic screen magnification software for low vision assistance.

Low vision patients should undergo low vision rehabilitation for proper training, environmental modification, orientation, mobility training, counselling and selection of suitable low vision aids to accomplish vocational and avocational activities independently. Visual aids help to improve both sight and quality of life for low vision patients.

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Low Vision Aids (Distance)

Low vision aids are designed to improve visual performance and provide enrichment of daily experiences. Low vision aids can be optical, non-optical and electronic devices.

Distance Optical Aids:

When conventional lenses cannot provide required visual range, aids that have optical properties will be capable of promoting better visual performance. Telescope is an optical instrument that improves the resolution of an object by increasing the size of the image projected on the retina by making things at distance appear to be closer. The use of telescopes can help individuals in their daily and social activities such as watching television, reading white boards, street signs, finding entrances from a building bus number, traffic signal, building numbers, billboards and menu boards. Advantages of the telescope as low vision aids include being simple and easy to bring along while the disadvantages are restriction of visual field, illumination, difficulty in locating and focusing on objects quickly, only suitable for short term viewing, cannot be used when mobile, limited depth of focus and expensive. In order to use telescopes more effectively, special skills and training are required.

Types of telescope

  • Keplerian or Galilean
  • Monocular or binocular
  • Hand-held, spectacle-mounted or clip-on

Keplerian Telescope

Keplerian telescope with convex lenses, providing high magnification and a wider field of view for individuals with low vision.An optical system that uses two convex lenses. Image produced by Keplerian was real and inverted which required a prism to reverse the image. Therefore it is heavier, longer and costs more compared with Galilean. Keplerian provides a greater visual field and better optical quality than Galilean.

 

 

Galilean Telescope

An optical system that uses one convex lens which is closest to the object and one minus lens which is closest to the eye. Image produced by Galilean is real and upright. It is lighter, shorter, and cheaper than the Keplerian. Thus, is the first-choice prescription. It is suitable for people with peripheral field loss due to it providing a wider visual field.

Monocular or Binocular

Comparison of monocular and binocular telescopes, highlighting differences in portability and field of view for distance vision.Monocular telescope is indicated when there is a significant difference in visual acuity between the 2 eyes. It is advisable to use in the better-seeing eye. It is more compact, lightweight, and cheaper. Drawback associated with the monocular telescope was eye fatigue and lesser field of view compared to the binocular telescope. Binocular telescope is indicated when there is similar visual acuity in both eyes, with the purpose of increasing the visual field, and for nystagmus. Binocular telescopes will be heavier and expensive.

Hand-held telescope

Hand-held monocular telescope with adjustable focus, suitable for short-term viewing and mobility.It is light, compact and cheaper than the Galilean and Keplerian. It is suitable for short activities and could be a first prescription choice.

Spectacle-mounted telescope

Spectacle-mounted binocular telescope for hands-free distance vision enhancement, ideal for prolonged use.It is suitable for those who have hand-eye coordination problems and is very useful for prolonged activities or activities that require visualisation of details.

 

Clip-on

Clip-on magnifying lens attachment for eyeglasses, providing additional magnification for detailed close-up tasks.The clip-on model has both advantages. It is lighter than the spectacle-mounted model. However, the lenses can be scratched and the visual field can be reduced to further distances.

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