Eye Care In Modern Life

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1 Eye Care In Modern Life Dr. Dorothy Fan Department of Ophthalmology & Visual Sciences November 2009

2 Structure of the Eye Information age > 90% of sensory input Blindness is one of the most fearful disabilities

3 Structure of the Eye Nowadays, not just life and death but also Quality Enhancement

4 Structure of the Eye

5 Structure of the Eye Accommodation Camera: no presbyopia Eye: presbyopia after age of 40 Functional Visual system Camera Perception >> Camera

6 Refractive Errors & Refractive Surgery

7 Refractive error What is it?

8 Refractive Error A mismatch between the refractive power and the focusing distance of the eye

9 Myopia The refractive power of the eye is too much so that light focuses in front of the retina

10 Hyperopia The refractive power of the eye is too weak so that light focuses behind the retina

11 Astigmatism The refractive power is different in different meridian

12 Hong Kong Story Number of cases Age of onset Severity 90% of University students are myopic

13 Hong Kong Story Prevalence of myopia Kindergarten: 3.25% Primary school: 36.09%

14 Myopia Causes of myopia?? Nature Vs Nurture

15 Myopia Nature Genetic factors Interactive with environment

16 Myopia Nurture? Visual task e.g. reading, writing, TV, computer, etc. No definite conclusions yet

17 Correction of Myopia Spectacles Contact lens Operation

18 Correction of Myopia Spectacles Contact lens Operation

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20 Contact Lens At least 35 million contact lens wearers worldwide 10% of the US population trend in Hong Kong

21 Contact Lens Commonly used types Hard lens Rigid gas-permeable lens (RGP) Soft lens Daily wear Extended wear

22 Contact Lens Improvement in the past years More gas permeable material Better design Better fitting techniques Better after care products

23 Contact Lens Contact lens wear: overall

24 Contact Lens - Complications Change ocular surface environment Hypoxia Allergy & Toxic Mechanical trauma Infection

25 Contact Lens - Complications Complications develop esp with improper care Regular check up is required

26 Contact Lens - Care Self Check See Feel Look

27 Correction of Myopia Spectacles Contact lens Operation

28 Correction By changing the eyeball length By changing the refractive power Changing the power of the existing structure Adding extra refractive medium

29 Corneal Refractive Surgery Commonest refractive procedure Radial keratotomy (RK) Photorefractive Keratectomy (PRK) LASIK LASEK

30 Corneal Refractive Surgery In myopia, the refractive power is too strong for the axial length Light focuses in front of the retina

31 Corneal Refractive Surgery In myopia, the refractive power is too strong for the axial length Light focuses in front of the retina cornea is flattened Chinese were among the first to put stones on the eye at night to achieve a flatter cornea in the morning

32 Corneal Refractive Surgery In hyperopia, light focuses behind the retina cornea is steepened

33 Photorefractive Keratectomy Painful Delayed Re-epithelialization haze Keratitis Elevated Intraocular Pressure Regression esp for high myopia

34 LASIK State of the Art Laser Assisted Stromal In-situ Keratomileusis

35 LASIK good candidates Refraction +6D to -13D Astigmatism <6D Enough corneal thickness Small pupil

36 LASIK - Results FDA (less than -7D) Better than 20/20 = 85% Better than 20/40 = 99% Depends on patients pre operative refraction

37 Complications

38 LASIK - complications Common problems dry eyes, halos at night Flap complications and infections are rare but could be serious ~0.3%

39 Risk Vs Benefits

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41 Cataract Lens Within eye ball Behind the iris

42 Cataract Lens Main function: Focusing objects +10D (spectacle-equivalent)

43 Severity Cataract

44 Cataract Causes of cataract Congenital Traumatic Senile Drug induce Diabetes Others...

45 Cataract A major problem in Hong Kong Growing population Longevity Aging population

46 Cataract - Treatment Observation? Medication? Laser? Operation?

47 Cataract - Treatment Removal of the cataract lens + Correction of refractive error (+10D = 1,000 degree)

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49 Guidelines for VDT Use Maintain visual comfort by proper ambient lighting Place VDTs away from windows and overhead lights. Clean screen to improve visibility regularly Proper working distance

50 Guidelines for VDT Use Top of VDT is slightly below eye level Blink eyes regularly Relax accommodation by looking at distant objects (30s every 30 mins) Maximize contrast

51 Guidelines for VDT Use Place reference material close to screen Use single-vision glasses instead of bifocal or progressive lens Rigid instead of soft contact lens Polarized, tinted or dark glasses for people with migraine

52 Guidelines for VDT Use With proper visual hygiene, one can enjoy trouble-free computing

53 Structure of the eye Refractive errors Contact lens Refractive surgery Cataract Computer eye care