Glass Prescriptions

The prescription in attached media below reads, Right eye , +2.50 Dsphere with -1.0Dcylinder at 180 degrees axis.
Left eye ,+1.50 Dsphere with -1.0 Dcylinder at 180 degrees axis.
With ADD of +2.0Dsphere for near.

Types of Bifocals lens

1.Kryptok_fused bifocals lens are most popular, less expensive and dividing line isn't seen easily.
2.Executive_one piece bifocals lens are mono centric, minimal or no prismatic effect, wide field of view for reading and no chromatic aberration.
3. 'D' fused bifocals lens are minimal prismatic effect, technically the most advanced bifocals and inconspicuous dividing line and are more expensive lenses.

ADD Power

Include is the in addition to power given for the amendment of presbyopia for performing close errand like perusing. Include power can go from +0.75 to +3.50 diopters. While composing solution , the add power is arithmetically added to the round part of the medicine. Tube shaped power and hub remains un changed.

Find out cylindrical lenses

To see whether a specific focal point is round and hollow, hold the glasses at 50_55 cm and take a gander at a straight line through the viewpoint. Move the focal point and watch the snapshot of the focal point. In the event that the lines seem to move in same heading as the focal point, then it's a sunken focal point. In the event that the lines seem to move in inverse heading then it's curved focal point. These round and hollow focal points are utilized to right astigmatism, are generally present alongside hyperopia and nearsightedness.

Cylindrical Lenses

These lenses are curved more in one direction than other. All the cylindrical lenses have axis. The axis refers to the orientation of the cylindrical area of the lens.The axis can be anywhere from 0 to 180 degrees, with 90 being the vertical meridian.

Concave Lenses

Concave Lenses are thinner in the center and thicker at the edges. Light rays are diverged. These lenses are used in correction of Myopia. These lenses are indicated with minus (-) sign on prescriptions.

Convex Lenses

Convex Lenses are thicker in the center and thinner at the edges. Light rays are converged towards a central point. These lenses are used in correction of hyperopia. These lenses are indicated with plus (+) sign on prescriptions.

Types of Frames

There are many different types of frames. The variations in type are based on the material from which the frames are made, their style, and the purpose for which the frames are designed.

Half eye frames

The half eye or reading eyeglasses are commonly prescribed for prebyopic patients. They can focus on things at a distance by looking over the lens without having to remove their eyeglasses.

Rimless Frames

There are some frames which provide no, or only partial, peripheral support for the lenses. These are called rimless or semi rimless frames. These are constructed in several different ways. These frames consists of a shallow groove at the edge of lenses into which a nylon cord fits. Each end of nylon cord is attached to the frame. These frames are also called supra frames.

Metal Frames

In metal frames, the temples and the front are made of metal, except the portion of the temple that fits the skull. Metal frame is aquipped with adjustable nose pads.

Plastic Frames

For years, the most common frames were made from a cellulose acetate materials called zyl. Recently, new plastic material have been used for manufacture of frames. Each material has unique properties that enhance fabrication, safety, or colorization.

Riding Bow Temple

Riding Bow Temple has a thin, long plastic temple wrapping around the ears. It is usually thin and mostly used for children's frame. It is more difficult to remove.

Skull Temple

The most common type of temple is called skull temple. It has bent and unbent versions. The skull temple is most comfortable for those people who wear their glasses for long periods of time. It fits easily on the ear and bends slightly to fit the skull.

Library Temple

The library temple is straight and pressure in used to held them on. This type of temple was developed for people who need to remove and replace their glasses many times during the day like near vision reading glasses.

The Temple

The temple of the frame is the long portion that supports the frame on the ears. It is also known as earpiece. Temple length is measured in millimeters. There are a variety of different styles of temple.

Eye wires

Each frame has opening for two lenses.
A right lens and left lens. The frame that holds the lens is called a eye wire. And the temple of the frame is the long portion that supports the frame on the ears. It's also known as earpiece. Temple lens is measured in millimeters . There are a variety of different styles of temples.

Comfort fit bridge

It is a solid saddle type bridge used on metal frames. Adjustable pads are present to provide control over adjustments that are need on any of the solid bridge.

Saddle Bridge

The saddle bridge allows the nose to make continuous contact with the front of frame. It has smooth rounded curves. It rests on the top and sides of the nose.

Keyhole Bridge

Keyhole bridge looks like the keyhole in the door. The bridge out line isn't continuous, it has small cut out section on either side. This means the nose doesn't make continuous contact with the front of the frame in the area called nasal crest.

Bridge Type

There are different types of bridges . Adjustable nose pad may be attached to the bridge. A special bridge insert of molded plastic, some times known as a form fit bridge, may also be used.
In plastic frames, the bridge and nose rest area may be molded into the frame. The bridge in plastic frames may be further classified into the keyhole bridge and the saddle style bridge.

The Bridge

The Bridge of the frame front serves two function. First, it supports the glasses on the nose. Second, it connects the two lens holders.

Ophthalmic Frame Materials

Most plastic frames are made of Zylonite, cellulose propionate or polyamide. The Metal frames are usually made from nickel silver and Monel. Titanium frames have high tensile strength and ultra lightweight and impressive corrosion resistance . But it is expensive.

Hi-Index lenses

High index lenses polymers with an index higher than 1.58. High index lenses require flatter curve than their low index lens materials, resulting in thinner and lighter lenses. High index material tends to have a lower abbe value which results in chromatic aberration. AR Coating are usually recommended for high index lenses to eliminate these reflections.

Polycarbonate glasses

Polycarbonate is the same material used for bulletproof glasses. It is the most impact of lens material. Polycarbonate is the material of choice for safety glasses and for children. With an index of 1.59, polycarbonate also produces thinner, lighter lenses than glass or plastic. Polycarbonate has ability to give uv protection.

CR-39 lens

CR-39 (Columbia Resin) is also known as plastic or hard resin. Lens made of CR-39 are much lighter than  glass. But CR-39 is less scratch resistant and must be coated to improve index: 1.498.Advantages of these lenses are :
Lighter than glasses, readily tintable, less like to fog, suitable for children and one eyed patients.

Ophthalmic Lenses

Glass is most stable, scratch resistant  material which provide the best optical quality of all lens materials. Glass is easy to break than  other lens materials and  hence the lenses made of glass must be tempered  or  heat treated to give them more strength and make them safer to wear. Glass is available in a number of indices of refraction.

Cataract

Any clouding of lens or  insult of lens is called cataract. Cataract is the most  leading  cause of blindness in world. Causes of cataract are  age related, because of injury, by using drugs, diabetic long time, mal neutration, chronic uveitis, electrical shock, etc.

Congenital Glaucoma

It is present at birth. It may occur because of a abnormal shape of the anterior chamber angle. It is called as infantile when it is present within the first year of life.
It's mostly a bilateral condition. It's also associated with high myopia. It is associated with many systematic conditions.

Scratch resistant / Hard coating

Plastic lenses are lighter than traditional glass lenses but they scratch more easily. Scratch resistant lenses can irritating for the wearer and look ugly. Scratch resistant coating are available to protect against damage and prolong lens life.

Anti-reflecting coating on Spectacle Lenses

Spectacle lenses can be provided with anti reflection coating, which will eliminate distracting reflections from the lens surface. Reducing reflected light is particularly helpful for computer users and for night driving.
Anti reflection coating also improves the cosmetic appearance of the glasses can make thick lenses look thinner.

Photo Chromatic Lenses

These lenses react to light so that indoors or in dull condition they they have a light tint, and in bright light they darken to eliminate glare and protect the eyes from uv rays. They have two colors photo grey and photo brown.

Interpupillarry Distance

IPD is an important measurement for selecting frames, alinging optical centers, calculating induced prism in high power prescriptions and adjusting binocular optical instruments like slit lamp, indirect ophthalmoscope etc.

Presbyopia

It is a term used to describe the condition in which a patient's amplitude of accommodation has decreased to a point where clear vision at the near point is difficult.
The amplitude of accommodation gradually decrease with age. In India presbyopia occurs around the age of 38-39 years.

Eye

Human eye is one of the five sense organ.
The eyes allow us to see and interpret the shapes, colors, and dimensions of objects in the world by processing the light they reflect or emit.
We use our eyes in almost in every activity we perform, wether reading or writing, working on a computer, watching television, or driving a bike.

How to install eye drop

Sit or lie down and tilt your head backward.
Place your index finger on the soft spot just below the lower  lid, generally pull down to form a pocket and look up.
Squeeze one drop into the pocket in your lower lid.
Close eye for 2-3 minutes without blinking .
Blot around eyes to remove any excess.

Orbital Cellulitis

It's an acute infection of the tissues surrounding the eye. It's caused due to spreading of bacterial infection from sinuses.
It's also caused due to spread infection from stye or injury to the eyelids.
In children it is spread  infection from sinus caused by organism like  Hemophilus influenzae, Staphylococcus aureus and Streptococci

Eye Exercise

These are some eye exercises:
Blink eyes few times.Close the eyelids , rolls eye behind closed eyelids clockwise and then anticlockwise. Take a deep breath and open the eyes when releasing breath. Use lubricating eyedrops while you feel irritation, dryness, itching or burning sensation.

Blood Supply to Eye

The major blood supply from the eye comes from ophthalmic artery. The lateral muscular branch of the ophthalmic artery supplies the lateral rectus, superior rectus, and superior oblique muscle.
The medial muscular branch supplies inferior rectus, medial rectus, and inferior oblique muscle.

Progressive Lenses

These lenses are used for correcting presbyopia but they don't have visible dividing line between the distance and near portion.
Instead they have a graduated section in which the power of the lens progresses smoothly from one distance to near, allowing the wearer to see clearly at all distances.

Bifocals

Bifocal lenses contains two optical corrections with a distinct dividing line between the two parts. The most common use of bifocals is for presbyopia.
The upper part of the lens corrects distance vision the lower half is for near vision.

Chemical burn

If a chemical falls in the eye, the first step is to irrigate eye with clean water. Irrigation of the eye should be  continued for about 15-20 minutes and then should be rendered to the nearest health center at the earliest.

Extraocular muscles

The six muscles that surrounds the eye and control it's movement are known as intraocular muscles. The primary function of four rectus muscles is to control the eye's movement from left to right and up and down.
The two oblique muscles move  and rotate the eyes inward and outward.

Scleritis

It's  a chronic, painful and potentially blinding inflammatory disease. It's commonly associated with systemic autoimmune disorders like rheumatoid arthritis ( joint pain).
Scleritis may be classified into anterior and posterior.
Posterior scleritis is very uncommon and can cause retinal detachment.

Avoid Spreading Conjunctivitis

1. Disinfect surfaces
2. Avoid touching the face again and again
3. Wash hands frequently
4. Don't share towels and washcloths
5. Don't use handkerchiefs, using tissue is best
6. Avoid shaking hands

Chalazion

It's chronic inflammation caused due to not flowing meibomian gland secretion. It's seen as round, painless, hard lessons on the eyelid.
It's associated with chronic meibomitis.In early stages warm compresses and lid massage are advised.
Surgery incision and currettage can performed if it decreases or recurs after sometimes.

External Eyelid Stye (Hordeolum Externum)

It is an acute bacterial infection of the Zeis glands. It present with painful swelling with pus formation at the lid margin.
Hot compress can be given to reduce symptoms. It may need epilation of the infected eyelashes or excision and drainage of the abscess.

Meibomitis

It is a chronic inflammation caused due to blockage of meibomian gland  secretion. Secretion can be shown out  from the opening areas on application of pressure on tarsus. Oily secretion can be seen on the meibomian gland orifices. It is always bilateral. Patients complaints of itching, burning and foreign body sensation.

Eye injury

Eye injury is one of the most common cause of unilateral blindness in the world.
It mostly affects the people in working age group in developing countries of the world.
Eye injury can occurs in a wide range of setting like household, roads, industries, sports etc.

Astigmatism

It is  a condition when parallel rays coming from infinity after refraction through the eyes will forms two focul lines instead of point focus on retina.

Eye Health / Blindness Astigmatism

Parallel rays coming from infinity after refraction through the eyes will focus one line behind  the retina and other behind the retina when accommodating is at rest.

Hyperopia (Farsightedness

Parallel rays coming from infinity after refraction through the eyes will focus behind to the retina when the accommodation is at rest.

Secondary Glaucoma

Secondary glaucoma refers to any case in which another disease cause or contributes to increased eye pressure, resulting in optic nerve damage and vision loss.
It can occur as a result of an eye injury, inflammation, tumor, or in advanced cases of cataract or diabetes.

Normal-Tension Glaucoma

It is also called low tension or normal pressure glaucoma. In this condition the optic nerve is damaged even though the eye pressure is not very high.

PRIMARY OPEN-ANGLE GLAUCOMA (POAG)

It is caused by the slow clogging of the drainage canal, resulting in increased eye pressure.
It develops slowly and is a lifelong condition.

Cornea

Cornea is a transparent layer ,dome shaped structure and outer most layer of the eye. It protect the inner parts of the eye. It gets it nourish from limbal cells, aqueous humor and tear films.

TEAR FILM

Tear film keeps our eye smooth and and moist and help in spreading tears in eye during blinking.
It protect us from infection, injury and dust.

Limbus

The junction between cornea and sclera is called limbus. The cornea is transparent tissue which allows light to enter clearly.

Sclera

The sclera is the tough , opaque tissue that gives protection to the internal parts of the eye. Six extra ocular muscles that controls the eye movements and the optic nerve are attached to the sclera

Crystalline Lens

The crystalline lens is located just behind the iris. Its main function is to focus light on the retina. The lens is suspended behind the pupil with the help of zonules.

vitreous humour

The vitreous is a transparent gel that fills the eye behind the lens. It is composed mainly of water and comprises about 2/3 of the eye's volume, giving it from and shape.

Optic disc

The optic nerve transmits electrical impulses from the retina to the brain. When examining the retina through the pupil, a portion of the optic nerve can be seen. It is known as optic disc. There are no cones and rods on this spot.

Myopia (Nearsightedness

Myopia is a refractive condition when parallel rays coming from infinity after refraction through the eyes will forms point focus infront of retina when accommodation is at rest.

Squint

Squint is a congenital issue where the eye is deviated either temporal or nasal side.
It can be corrected with spectacles or eye exercise.

Varicella-Zoster Virus

This is the virus which affects the frontal area, head, nose,waist, etc.
It also effects on eye . With this infection there is high fever.

Fungal Keratitis

Fungi enter in the corneal stroma through defect in epithelium.
Then multiple and caused tissue death and an inflammatory reaction.
The epithelium defect mostly results from trauma in the eye with plant materials.

Bacterial Keratitis

Bacterial keratitis is a sight threatening disease. It progress rapidly and cause corneal perforation within 24- 48 hours due to some bacterial infection.
The most common bacteria which cause infection are streptococcus, pseudomonus, accanthamobia, etc.

Allergic conjunctivitis

Allergic conjunctivitis may cause due to intolerance to substances such as cosmetic, perfume, or drugs.

VIRAL CONJUNCTIVITIS

The viral conjunctivitis is commonly caused due to a adeno virus.

Eye injury

Ocular trauma is one of the most common causes of unilateral blindness in the world.
It mostly affects the people in working age group in developing countries of the world.
Ocular trauma can occurs in a wide range of setting like household, roads, industries , sports, etc.

ulcerative blepharitis

This condition is due to infection of the lid margin with coagualase positively staphylococcus, superimposed on predisposed conditions.
There is superlative inflammation of the ciliary follicles along with the glands of Zies and Moll .
Yellowish crusts are deposited at the roots of eyelashes by which the lashes are glued togather.
On removal of crusts, small ulcer appear around the base of lashes which bleed freely.

Rosacea keratitis

It occurs usually in elderly women and is not common in this country. There are yellowish white infiltrates in the cornea, with small superficial ulcers.The cornea soon becomes vascularized.
The eye is very irritable with profuse lacrimation. Recurrences are common. Actual etiology is not known, but may be allergic in nature.

Retinal detachment

A retinal detachment occurs when the sensory retina and retinal pigment epithelium layer separate.
Retinal detachment is considered an  ocular emergency that requires immediate medical attention and surgery.
It may occur in patients with high myopia, diabetic retinopathy, premature birth, eye injury, holes in the retina and severe inflammation in the back portion of the eye.
Symptoms may light flashes, wavy vision, veil or curtain obstructing vision, floaters, sudden decrease of vision, etc.

Choroid

Choroid is the vascular layer of the eye and posterior most part of the uveal tract.
It is spread out from Ora seretta to optic nerve and lying between retina and sclera. The main function of choroid is the blood supply to rods and cones.
It gives neutration to the retina.It also helps to absorb excessive amount of light which is reflected from retina.

Viral keratitis

In Herpes Simplex virus (HSV) the infection of the cornea , the corneal lesions that look like the veins of a leaf are seen.This is known as dendritic keratitis.
Repeated episodes of dendritic keratitis can cause permanent scarring, and loss of sensation of the cornea.
Recurrent dendritic keratitis is followed by disciform keratitis. It is characterized by central , disc shaped swelling of the cornea and by inflammation of the iris.

Vernal Keratoconjunctivitis

Vernal Keratoconjunctivitis affects mostly in children and it affects mostly people who are living in the dry and sandy areas.
Symptoms may papillae in the tarsel plates, limbal thicking, trantas spots on limbus, superficial punctate keratits, ropy discharge, etc.

Endophthalmitis

Endophthalmitis is an inflammation of the internal cavity of the eye ball.  Complication of endophthalmitis are intra ocular surgeries like cataract or any penetrating trauma, allergic reaction , and retained intraocular foreign bodies.
It is caused due to infection from bacteria, fungus, parasites, etc.