Selection of frame and lens on basic of occupation and age RAY ARBIND & VINITKUMAR Optometrist,SCEH Spectacle frame • A portion of the spectacles that holds the lens in their proper position before the eyes • Rests on the nose, balance on the ears and anchor around the ears Importance of frame Selection • • • • • Value for expertly prescribed spectacle lenses Vision and comfort Good cosmetic appearance Frame Adjustment Professional accordingly Frame Selection According to Demand • Age group: Small children, young adult, old adult • Profession: House wife, shopkeeper,medical practitioner, drivers,field worker • Refractive error: minus vs plus, low vs high. • Special purpose frame: ptosis frame , sport spectacles Cont.. According to Purpose • Prescription lens wear • Protective eye wear • Sports eye wear • Cosmetic eye wear Properties of ideal frame materials • • • • • Non-allergic Non-inflammable Inexpencive Durable Adjustable Frame selection according to Ocupation Driver • it is common for the vision standard to be at least 6/12 on the Snellen chart with both eyes open or in the only eye if monocular • When wearing spectacles for driving, it is highly recommended that users have an anti-reflection coating applied to reduce the effects of glare. • Plastic lens materials should be given • Avoid full frame and small frame to avoid ring scotoma Train Driver • Train driver will be required to have visual acuity of 6/9 in the better eye and 6/12 in the other eye and Normal colour vision • Train drivers will almost driving in differing climates and light conditions, therefore arrangements should be made to cover all eventualities. • It is recommended that a train driver has a pair of spectacles • With an additional pair of tinted lens Pilots • The entry requirements for the aviation pilots require a visual acuity, with spectacles or contact lenses, to be 6/9 in each eye with an ability to see 6/6 • Generally grey or brown tint should be given,but not darker than 80%. • Polarised filter is introduced the light in one direction • To deal with those who are presbyopic progressive lens allows a pilot to see at distance, intermediate and near • Plastic frame will be preffered Factory workers • Many people such as engineers, processing, cleaners, craftsmen etc. will work in a factory environment. • For worker work in hot climate,frames made from optyl,Kevlar or rubber are better • In chemical factory workers frames from polyamide is better option • In terms of ‘safety’ spectacles, they will have side shields attached to the sides of the frame to avoid any foreign objects entering the eye • The lenses supplied will be CR39,polycarbonate or Trivex Office Workers • The modern day in offices have become extremely reliant upon the use of computers • Not enough breaks can lead to dry eyes as a result of insufficient blinking ARC is strongly recommended • When an office worker reaches presbyopia,Progressive lenses may achieve favourable results • Plastic Lens materials will be preffered • Frame should be of plastic as well metal materials Teachers/Lecturers/Presenters • For people who have various visual requirements it can be beneficial to have multiple pairs of spectacles • In the classroom teachers standing,looking,walking,writing on the board therefore distance and near correction will be essential, as well as intermediate • Progressive lenses should be the first consideration Shop workers • Shop workers will have various visual requirements depending on their duties. • Progressive glass will be more useful than bifocal glass • Glass materials should be given in metal as well plastic frame Outdoor Activities • Occupations where much of the working day will be spent outdoors will require single vision as well bifocal according to the need. • For people such as gardeners, traffic, police, road workers etc.,such as photochromic lenses and plastic frame should be considered • When photochromic lenses are exposed to UV rays they darken and provide visual comfort in direct sunlight. • Tint became fades when moving to indoors and almost clear at night. Welders • Person who have hobbies of welding including car repair could be involved. • A variety of radiation hazards are presented • The protection recommended can be in the form of goggles, helmets or face shields are routinely worn during welding • These may provide head,eyes and neck protection from the intense radiation. Electrician • Plastic frame will the first choice • Metal frame should be avoided when electrical hazard are present • Side shields are necessary when eye injuries from the side are possible Sport Person • Polycarbonate is a material usually associated with lenses • Frames made from polycarbonate are primarily for sport or safety purposes. • When made for non-prescription purposes, wraparound frame and plano power are molded as one unit • Unfortunately, polycarbonate frames do not work well for conventional eyeglasses because of their resistance to adjustment Swimming • Water gets in the eyes and water changes the refractive power of normal spectacles • Use swimming goggles. Goggles may be fit with powered lenses • Contact lenses may be worn underneath plano goggles. • Use a goggle with back-surface antifogging properties Boating • Glare from the water • Use a polarizing lens, which also blocks UV light. • Use a sunglass lens that cuts out all UV light up to 400 nm. • Use thermosetting frame materials and plastic lens materials Mountain Climbing • Increased exposure to UV radiation beacouse of of less atmospheric absorption • Brightness of outdoor environment is more • Use UV-absorbing goggles that eliminate all wavelengths up to 400 nm. • For high altitudes where brightness is excessive, use sun lenses with approximately 5% transmission and a wraparound design or use sunglasses with side shields Frames selection in Special Cases • Pediatrics • Geriatrics • High refractive errors • Ptosis Frames for Paediatrics – Safety should be the main concern – Sturdy – Riding bow temple – Comfort temple with rope tied behind head – Spring temple – Plastic frame – Polycarboante or CR-39 lens are the lens for choice Frames for Geriatrics • Light weight frame • Light weight lens materials • Adequate size of bridge • Relatively larger frame • Large and adjustable nose pads Frames for High Myopia • Small, round frame shapes • Plastic frame • Avoid rimless • Reduce the vertex distance Aphakia and High Hyperopia •Sturdy, light weight, easily adjustable frame •Avoid frames with thick wires – increase ring scotoma •Adjustable pads •Select frame with relatively small eye size with symmetrical lens Ptosis Frame Ptosis frames have a wire or plastic crutch attached to the top eyewire to support the drooping eyelid. Half eye Frame • Half-eyes are frames made especially for those who need a reading correction but no correction for distance • Constructed to sit lower on the nose than normal glasses • Just to look under the lens for reading Common Maladjustment and their Remedies condition Possible causes Remedy Pads dig in to nose Pads too tight or small, small bridge Widen distance of pads, large pads Spectacle slide down on nose Pads do not fit flatly against nose Correct pads, make temple shorter Lashes touches lenses Temples too short Longer temple Eye wire touch cheeks Too great distance between pads Too great pantoscopic tilt Lenses too large vertically Brings pad closer Reduce pantoscopic tilt Smaller eye size Temple heart behind Ear Tension too great Larger temple Allergic reactions to frame materials • To reduce the possibility of a reaction for people who have a history of skin reactions to wearing frames • Use frame materials that are known to be hypoallergenic • Optyl material,Polyamide,Titanium,Stainless steel should be mainly preffered • If a person has an allergic reaction to nosepads,Gold-plated metal nosepads,Titanium nosepads,Crystal nosepads should be replaced to aliminate the problem • For allergic reactions to metal temples, use a temple cover • Temple covers come in plastic, vinyl, and silicone materials Lens Types Single vision lenses • A single vision lens has the same focal power across the entire lens surface • Use to correct myopia, hypermetropia, astigmatism Bifocal lenses • A bifocal lens consists of two parts: the upper segment is used for distance vision and the lower segment for near vision Trifocal lenses • A tri-focal lens is similar to a bifocal with the addition of a third segment generally incorporating intermediate power Progressive Lenses • A progressive power lens has no dividing lines as the focus changes • Visual comfort at all distances; distance, intermediate and reading Enhanced reading lenses • An enhanced reading lens provides a greater depth of focus than conventional single vision lenses for reading • Offers more flexibility in near working distance Lens Materials Crown Glass • Glass is used infrequently nowadays although still available for those who have a preference • It should never beused for children or monocular patients • Having refractive index of 1.52 and Abbe number 60 Advantage Scratch resistant Disadvantage Impact resistant High specific gravity 2.54 Columbia Resin-39 • CR39 is plastic materials.it is the most commonly used lens material • Having refractive index 1.49 and Abbe value 54-50 Advantage Impact resistant Low specific gravity 1.32 Disadvantage scratch resistant Polycarbonate • Polycarbonate is plastic materials,lighter in weight • Used in safety spectacles and for children’s spectacles. • Having refractive index of 1.58 and Abbe number 2830 Advantage Impact resistant Low specific gravity 1.21 Disadvantage scratch resistant Trivex • Trivex is plastic materials,thinner and lighter lens and more impact resistant (similar • Good optical properties and UV absorption • Having refractive index of 1.54 nad Abbe number 45 Advantage Impact resistant Low specific gravity 1.11 Disadvantage Scratch resistant Thank you
