Basic tools for eye examination are slit lamp and fundoscope also called as ophthalmoscope.Advanced techniques let us use computer,laser and ultrasound technology.Different eye tests involved in the routine eye examination are checking visual acuity by checking eye sight,visual field testing,pupillary exam,motility exam,external examination,slit lamp exam,IP testing,fundoscopy,color vision test and steroacuity testing.

First of all, the examiner assesses the patients visual acuity by checking vision using snellen chart.Other tests are briefly discussed below.

External examination:The examiner carefully observes both eyes thoroughly by everting both the upper and lower eye lids to get a clear view of cornnea and conjunctiva.The examiner asks the patient to shift gaze direction for a complete view of eye structures. Cornea maybe stained for a more careful analysis of eye surface.Green patches on the corneal surfaces that don't go away on blinking canbe corneal abrasions. A careful examination of the eye globe and its positioning within the eye socket can reveal eye abnormalities.For instance,protrusion of the eye ball(exopthalmos) can signal underlying Grave's disease,orbital inflammation or an orbital tumor. Finally,the appearance and position of eyes shouldbe checked e.g drooping of the upper eye lid(ptosis) could result from CN 111 palsy,horner's syndrome or myasthenia gravis.Ptosis is usually a result of weakened levator muscle of the upper eye lid or interfence with its nerve supply.

Slit lamp exam:Slit lamp biomicroscope provides a magnified look at the structures of the anterior chamber of the eye.The apparatus is used for examining the eye lids,conjunctiva,cornea,anterior chamber,iris,lens & viterous of the eye.The patient places the chin on the chin rest attached to the biomicroscope and the forehead forward against the forehead rest.After that the ophthalmologist sets the biomicroscope to get an accurate image.

Fundoscopy:A fundoscope or is needed for the test.Direct fundoscopy provides a magnified view of the posterior segment of the eye.It's useful in diagnosing diseases of the retina such as diabetic retinopathy & diabetic occlusion and for optic nerve pathology such as pappiledema & glaucoma.

Indirect fundoscopy allows the examiner to examine the posterior pole and retina periphery.It's useful in finding retinal hemmorhage,scars and retinal tears or breaks.

Visual field test:The purpose of testing visual field is to find any defect or injury along the visual pathway leading from the retina to the occipital lobe.Two formal methods for measuring visual fields are Goldman & Humphery visual fields.But confrontational field provides a gross assessment of the periphery.

Pupillary exam:The pupillary exam is intended to detect functional defects in the pupillary reflex arc and the neural circuitary.The neural circuitary allows the eye to respond to light via pupillary constriction.When a light stimulus is directed at either eye,both pupils respond in an identical pattern because of the equal bilateral innervation of the pupils.

Motility exam:This test is performed to check eye movements.The eye has 6 cardinal directions of movement that are controlled by 6 extra ocular muscles(EOM).

 Superior and inferior recti muscles control vertical eye movements.

Medial and lateral recti muscles  control horizontal eye movements.

Superior oblique muscle moves the eye inward and downward.

Inferior oblique muscle causes outward and upward eye movement.

Intraocular pressure testing:Normal values for intraocular pressure(IOP) range from 8-21mmHg.Abnormal values can range from as low as 0mmHg when the globe is ruptured to 40mmHg or higher in certain types of glaucoma.

There are different techniques for measuring intraocuar pressure.The most common are applantation tonometry, Schiotz tonometry and Manual assessment.

Applantation tonometer is an easy to use device usually found on most slit lamps.Schiotz tonometer is less accurate than applantation tonometer but its more available in the hospitals. Manual assessment is done when the tonometer is not available.The patient is asked to close both eyes.The examiner uses the index and middle finger of each hand to palpate the globe through the upper eye lid.Manual assessment shouldbe avoided if there is suspected rupture of globe or in patients undergone recent eye surgery.

 Color vision test:The test is used primarily to detect abnormalities in the retina or the optic nerve.Red-green color blindness is a result of abnormality in the retina.Standardized color plates that are Ishihard,HRRAO are commonly used which contain color dots.Other formal tests are Farnsworth D-15 and 100 hue test.

Steroacuity test:Steroacuity is a measurement of how well the two eyes function togather for depth perception and discernment of 3D objects.The patient wears polarized glasses.Our brain combines the two images to create a 3D image.Patients who suppress the vision in one eye wouldn't be able to discern any 3D effect.