High myopia.pptx

High myopia

1. High myopia Madiha nazly Optometrist/ coavs

2. Myopia  is a refractive defect or error in visual focusing. Images are focused in front of the retina and not on it, making distance vision difficult. When the visual error exceeds eight dioptres , it is referred to as  high myopia

3. High myopia is a relatively severe level of nearsightedness that can be associated with significant eye health complications. The term high myopia generally used to describe nearsightedness of -6.00 to -8.00 D or higher, which produces uncorrected visual acuity of 6/60 or worse . In other words In a healthy eye, light enters the lens of the eye and is refracted onto the retina to form an accurate, sharp image that the brain can decode. In short-sighted people, the refraction doesn’t work properly; the light is bent so that it focuses in front of the retina, creating a blurry image. This happens if the eye is the wrong shape – the eye may be too long, or the cornea might curve at the wrong angle

4. Inheritance In almost all cases, heredity plays a role in the development of high myopia . If both parents are quite nearsighted, their child has a greater risk of developing high myopia. But developing myopia isn’t purely a case of genetic inheritance. Our living environments play a part in determining whether the genes we carry will actually be triggered. The more we understand about these environmental factors, the more we can do to prevent myopia in future generations. There’s still a lot of work to be done in this area, but there are some factors that do seem to be linked to elongated eyeballs, which can lead to myopia. Scientists have found that time spent indoors, doing close-up work such as reading, is linked to a higher risk of short-sightedness, although researchers are yet unsure whether it’s the lack of daylight or the close-up work that is more of a factor. In any case, this is a risk factor that can be minimized in early childhood

5. Possible Etiologies of Myopia by Classification Nocturnal Myopia Significant levels of dark focus of accommodation Simple Myopia Inheritance Significant amounts of near work Unknown

6. Pseudomyopia Accommodative disorder High exophoria Cholinergic agonist agents Induced Myopia Age-related nuclear cataracts Exposure to sulfonamides and other pharmaceutical agents Significant variability in blood sugar level Degenerative Myopia Inheritance Retinopathy of prematurity Interruption of light passing through ocular media Unknown

7. Nocturnal Myopia Occurring under conditions of darkness or very dim illumination, N octurnal myopia is due largely or entirely to an increase in accommodation associated with the decreased accommodative cues in darkness. The accommodative dark focus appears to be relatively stable, at least over a period of days . In nocturnal myopia, the results of retinoscopy in a dark room may be shifted in the minus direction, compared with the standard manifest refraction . Patients who have nocturnal myopia often complain of difficulty driving at night and/or blurred distance vision at night.

8. Pathological myopia Degenerative or pathological myopia is generally high myopia that is congenital or of early onset. Corrected visual acuity may be reduced as a result of pathological changes in the posterior segment. Abnormal or adverse ocular changes in degenerative myopia can include : Vitreous liquefaction and posterior vitreous detachment Peripapillary atrophy appearing as temporal choroidal or scleral crescents or rings around the optic disc Lattice degeneration in the peripheral retina.

9. Tilting or malinsertion of the optic disc, usually associated with myopic conus Thinning of the retinal pigment epithelium with resulting atrophic appearance of the fundus Ectasia of the sclera posteriorly (posterior staphyloma ) Breaks in Bruch's membrane and choriocapillaris , resulting in lines across the fundus called "lacquer cracks" Fuchs' spot in the macular area.

10. Lacquer cracks

11. Fuchs' spot

12. High myopia itself does not generally lead to vision loss. However, people with the condition have a greater risk of developing several other vision-threatening conditions, including. Retinal detachment Glaucoma Cataracts

13. The retina's center (macula) thins with age. While this does not affect side (peripheral) vision, the ability to focus on a particular object (like reading a sign) diminishes and is eventually lost. Retinal thinning can also lead to tears and holes, which can cause the retina to detach. (Learn more about retinal detachment.) The retina can split, a condition called myopic retinoschisis  (MRS). Layers of the eye under the retina can degenerate or crack, allowing new, faulty blood vessels to grow under the retina (a process called  choroidal neovascularization, or CNV). The vessels can bleed and scar, with small scars causing minor macular damage and larger ones more significant problems. Increased eye pressure may lead to glaucoma. Cataracts are more likely to develop. The eyes become more susceptible to injuries and other traumas.

14. Progressive high myopia generally does not lead to permanent vision loss or blindness, however axial elongation of the eye accompanied by progressive high myopia can lead to thinning of the light sensitive tissue known as the retina, which in turn can lead to retinal tears and retinal detachment. It can also lead to pathological myopia, where thinning of the macula occurs which can lead to permanent, even devastating vision loss.

15. Management of high myopia Spectacle correction Contact lens Refractive surgeries Clear lens extraction And in the last the most latest technique is ORTHO K

16. Orthokeratology ( orthok ) has been shown to have the greatest effect.. Orthokeratology is one of a class of therapies known as vision shaping treatments . OrthoK involves wearing orthokeratology lenses ( ortho k lenses) during sleep, which gently reshape the surface of the cornea of the eye. Upon removal in the morning, clear vision is achieved which often lasts the entire day into the evening .