2. What is a Spectacle?
Spectacle is defined under British standard as an
optical appliance comprising lenses and a frame
with sides extending towards ears.
Spectacles is a common, cheap and easy method of
prescribing corrective lenses in patients with
refractive errors and presbyopia. Working
knowledge about spectacle lenses , frames and
process of dispensing will help an ophthalmologist
to give exact instructions to the optician. This will go
a long way in ensuring patient satisfaction with
glasses.
3. Nine Essential Parts of Eyeglasses
1. Rims
The rims lend form and character to your eyeglasses—
they also provide function by holding the lenses in place.
2. End pieces
The end pieces are the small parts on the frame that
extend outward and connect the lenses to the temples.
4. 3. Bridge
The bridge is the centre of the frame that rests on your
nose and joins the two rims together.
4. Hinges
The hinges, which sit between the end pieces and the
temples, allow you to close your glasses by folding the
temples inward.
5. Lenses
Lenses are the clear pieces of glass, plastic or other
material held in place by the rims. The lenses are crafted
and shaped with your unique prescription to help you see
clearly.
6. Screws
The screws are the small metal fasteners near the hinges
that connect the end pieces with the temples.
7. Nose pads
The nose pads are the round plastic pieces under the
bridge that sit on your nose. They give your glasses a
more comfortable and secure fit.
5. 8. Pad arms
The pad arms extend from the rims and hold the nose pads
in place. They’re adjustable to fit the natural shape of your
face.
9. Temples
The temples are the long arms on the side of the frame that
fit over your ears for a snug fit.
LENS ENHANCEMENTS
UV protection
Scratch resistance coating (SRC)
Anti reflection coating (ARC)
Tinting
Hydrophobic coating
6. Points to be considered in lens fitting:
1. Vertex Distance - Should be specified for higher
prescription. Pupillary alignment : Pupils should be close
to the optic centre of each lens to take full advantage of
refractive correction given.
2. IPD : Interpupillary distance should be measured both
for distance and near.
3. Fitting plane of lenses – lenses should be in a plane
perpendicular to the visual axis, ideally fitted 15.7mm in
front of cornea which corresponds to anterior principal
focus, but practically fitted as close to the eye as
possible.
4. Optical centres: Marking is very important for proper
fitting as it should coincide with visual axis. Hold the lens
against a cross line chart horizontally or vertically and
move until one gets an unbroken crosstaste and budget
of the patient.
7. Conclusions
Spectacles still form a major share in optical correction of
refractive errors and presbyopia. Wider choices are available in
frames and lenses. Selection depends on taste and budget of the
patient, occupational condition and requirement – Finally the
wearer should see well and look good.
