A PAPER PRESENTATION AT THE 2017 NIGERIAN OPHTHALMIC NURSES ASSOCIATION ANNUAL GENERAL MEETING AND SCIENTIFIC CONFERENCE, GOMBE, 2017 VISION 2020 – THE JOURNEY SO FAR (2ND TO 6TH OCTOBER, 2017) PRESENTED BY GBAIYEGUN JOHN FOLORUNSHO (NONA , ASORN Member) COURSE CO-ORDINATOR – REFRACTION TRAINING, NATIONAL EYE CENTRE COMMUNITY DEPARTMENT, KADUNA - NIGERIA
Preventable blindness is one of the most tragic and wasteful global problems, restricting the employment and life prospects of otherwise healthy people. Blindness, uncorrected or poorly corrected vision affect every aspect of social and economic welfare of people and countries. It impedes learning in children and adult it difficult or impossible to find employment leading to burden on others.
In Africa, blindness rate is seven times higher at 1.4% than in developed countries due to lack of services. In developed countries practitioner to population ratio is approximately 1:10,000 and in developing countries ratio is 1:600,000 and in much worse in many rural areas at a ratio of 1:millions. It is estimated that 2.3 billion people worldwide have refractive error, vast majority of these could have their sight restored by spectacles, but only 1.8 billion people have access to eye examinations and affordable correction leaving with uncorrected error causing blindness and impaired vision.
Many are not aware that there is a cure for their compromised vision, harness one to provide treatment or cannot afford the appliances they need. For children this issue is particularly critical as vision impairment is a major impediment to education and future employment.
What is needed?
To eliminate uncorrected refractive error is through the development of all aspect of a self sustaining system including human resource to provide refractive error service and spectacles to correct vision. A simple eye examination and spectacle can eliminate 12% of world blindness and over 50% of impaired vision.
Trained eye care personnel + Affordable spectacles = PEOPLE WHO CAN SEE
Our ability of seeing object in visual field by receiving light reflected from them, those object do not provide light and this explain why we cannot see in the dark because no light from the object to reflect. Light travel in a straight line and while it travel in same direction. Beam of light consist of light rays. Beam of light can be parallel (same direction, divergent) spread out or convergent i.e. Coming together. Light can be reflected i.e. Bounce off or Refracted i.e. Bent or change direction. Law of Reflection state that the angle of reflection is equal to the angle of incidence.
Law of Refraction is change of direction of light when it passes from one transparent medium into another of different optical density. But in clinical practice RFRACTION requires the various testing procedures employed to ensure the refractive errors of the eye to provide the proper correct.
Objective method – In objective refraction examiner determine refractive state of the eye on the basis of optical principles of refraction without the need of subjective responses on the part of the patient.
Subjective method – Subjective refraction examiner determine the refractive state entirely on the basis of patient’s subjective response.
In keratometry refractive power of cornea is determined in each of the two principal corneal meridians
Keratometry provide the practitioner with information about astigmatism of the eye but not information about the spherical ametropia.
Retinoscopy provide information concerning both spherical ametropia and astigmatism.
Basic Refraction Routine Rules
Start with RE before LE
There should be good source of light to test type (subjective)
Dim illumination or light off (objective)
Basic rules of ophthalmoscopy observed.
Pick target at line above best VA
Preferably at extremities
Use vertical alphabet target for sphericals correction
Do not block patient view at Retinoscopy
Insert Ret-lense +1.50 bilaterally
Ask simple specific question
Introducing + lenses question is with or without or the same
Introducing –ve lenses question should be without or with or the same
Neutrality or endpoint is pt saying the same or without.
Respect the rule of maximum plus and minimum minus.
. Static Retinoscope
. Streak Retinoscope
In streak, patient is seated 6 metres or 20ft away from target
Fit trail frame and be sure lens aperture are centred on pupils with patient gazing strait.
Patient view should not be blocked
Ophthalmoscope principles observed
Retinoscopy is done Binocularly no eye is ocluded
Insert working lens or Ret-lenses +1.50 BE
Identify the ret-reflex
Identify direction and type of movement
Identify type of lenses to neutralise type of movement seen
Identify endpoint, neutrality or point reversal
If with movement seen, neutralise with +ve lenses sphere
Add spherical lens until movement stop/neutralise
Note the power of lens and record
If movement is against neutralise with –ve sphere
Note the power and record having neutralised
Change your streak and scope, if there is movement
Neutralise with cylindrical lense –ve
If no movement, patient is not astigmatic
Objective refraction is the estimate way of determining patient refractive correction.
Subjective Refraction Procedure
This is done monocularly i.e. One eye closed
Good source of light on test type
Pick target on line above best VA
Ask simple specific question
Start introducing plus lens before –ve lense
Lenses are picked according to magnitude of error or VA
If plus lense are accepted from beging
Add more plus lense in the series of +025
Until patient say without or both the same
Then you are at point of reversal, end point or neutrality.
Then record the power with the RE or LE
With the achieved VA
Take into cognisance the rule of maximum plus and minimum minus
Then turn to the second eye and do the same
Then let the patient read the smallest chart to check-up the level of correction
Then patient glass orientation is done
To ascertain comfortability of the refraction
Then arrange to get a fitted, comfortable and affordable glasses for the patient.
Subjective Refraction is the most accurate way of determining patient refractive correction.
Progressive and irreversible loss of accommodation with age which affect virtually everyone that necessitate spectacle correction for near vision by age 40 – 45 and earlier 35 – 40 in countries closer to equator. During presbyopia prescription reading addition is determined by patient need how near do they have to work and what near task do they have to perform.
GUIDELINE FOR PRESBYOPIA CORRECTION
40-45 NEAR ADD +100- +150
45-50 NEAR ADD +150 - +200
50-55 NEAR ADD +200 - +250
55+> NEAR ADD +250 - +275 above
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