Medical brain notes 32

  History A complete history includes four aspects: 1.   Family history.  Many eye disorders are hereditary or of higher incidence inmembers of the same family. Examples include refractive errors, stra-bismus, cataract, glaucoma, retinal detachment, and retinal dystrophy. 2.   Medical history.  As ocular changes may be related to systemic disorders,this possibility must be explored. Conditions affecting the eyes include diabetes mellitus, hypertension, infectious diseases, rheumatic disorders, skin diseases, and surgery. Eye disorders such as corticosteroid-induced glaucoma, corticosteroid-induced cataract, and chloroquine-induced maculopathy can occur as a result of treatment with medications such as steroids, chloroquine, Amiodarone, Myambutol, or chlorpromazine (see table in Appendix). 3.           Ophthalmic history. The examiner should inquire about corrective lenses,strabismus or amblyopia, posttraumatic conditi...

  Visual Acuity Visual acuity, the sharpness of near and distance vision, is tested separately for each eye. One eye is covered with a piece of paper or the palm of the hand placed lightly over the eye. The fingers should not be used to cover the eye because the patient will be able to see between them (Fig. 1. 4 ). The  general practitioner  or  student  can perform an  approximate test ofvisual acuity . The patient is first asked to identify certain visual symbolsreferred to as optotypes (see Fig. 1. 2 ) at a distance of 5 meters or 20 feet ( test ofdistance vision ). These visual symbols are designed so that optotypes of a cer-tain size can barely be resolved by the normal eye at a specified distance (this standard distance is specified in meters next to the respective symbol). The eye charts must be clean and well illuminated for the examination. The sharpness of vision measured is expressed as a fraction: Normal visual acuity  is 5/5 (20/20), or 1...

  Ocular Motility With the patient’s head immobilized, the examiner asks the patient to look in each of the  nine diagnostic positions of gaze:  1, straight ahead; 2, right; 3, upper right; 4, up; 5, upper left; 6, left; 7, lower left; 8, down; and 9, lower right (Fig. 1. 5 ). This allows the examiner to diagnose strabismus, paralysis of ocular muscles, and gaze paresis. Evaluating the  six cardinal directions of gaze  (right, left, upper right, lower right, upper left, lower left) is sufficient when examining paralysis of the one of the six extraocular muscles. The motion impairment of the eye resulting from paralysis of an ocular muscle will be most evident in these positions. Only one of the rectus muscles is involved in each of the left and right positions of gaze (lateral or medial rectus muscle). All other directions of gaze involve several muscles.

  Binocular Alignment Binocular alignment is evaluated with a  cover test . The examiner holds a point light source beneath his or her own eyes and observes the  light reflec-tions in the patient’s corneas  in the near field (40 cm) and at a distance (5 m).The  reflections  are normally  in the center of each pupil.  If the corneal reflection is not in the center of the pupil in one eye, then a tropia is present in that eye. Then the examiner covers one eye with a hand or an occluder (Fig. 1. 6 ) and tests whether the  uncovered eye  makes a compensatory movement. Compen-satory movement of the eye indicates the presence of tropia. However, there will also be a lack of compensatory movement if the eye is blind. The cover test is then repeated with the other eye. If tropia is present in a newborn with extremely poor vision, the baby will not tolerate the good eye being covered.

  Examination of the Eyelids and Nasolacrimal Duct The  upper eyelid  covers the superior margin of the cornea. A few millimeters of the sclera will be visible above the  lower eyelid.  The  eyelids  are in direct con-tact with the eyeball. Stenosis of the nasolacrimal duct produces a  pool of tears in the medialangle  of the eye with  lacrimation  (epiphora). In inflammation of the lacrimalsac, pressure on the nasolacrimal sac frequently causes a reflux of  mucus orpus from the inferior punctum.  Patency of the nasolacrimal duct is tested byinstilling a 10% fluorescein solution in the conjunctival sac of the eye. If the dye is present in nasal mucus expelled into paper tissue after two minutes, the lacrimal duct is open.

  Examination of the Conjunctiva The conjunctiva is examined by direct inspection. The bulbar conjunctiva is directly visible between the eyelids; the palpebral conjunctiva can only be examined by everting the upper or lower eyelid. The normal conjunctiva is smooth, shiny, and moist. The examiner should be alert to any reddening, secretion, thickening, scars, or foreign bodies. Eversion of the lower eyelid. The patient looks up while the examiner pullsthe eyelid downward close to the anterior margin (Fig. 1. 7 ). This exposes the conjunctiva and the posterior surface of the lower eyelid. Eversion of the upper eyelid. Simple eversion (Fig. 1. 8 ). The patient is asked tolook down. The patient should repeatedly be told to relax and to avoid tightly shutting the opposite eye. This relaxes the levator palpebrae superioris and orbicularis oculi muscles. The examiner grasps the eyelashes of the upper eyelid between the thumb and forefinger and everts the eyelid against a glass rod or swa...