As with any medical encounter, the initial part of the evaluation begins with a thorough history. The components of the history are similar to a general medical history but focus on the visual system:

• Chief complaint (CC)

• History of present illness (HPI)

• Past ocular history (POH)

• Eye medications

• Past medical and surgical histories (PMH / PSH)

• Systemic medications

• Allergies

• Family history (FH)

• Social history (SH)

• Review of systems (ROS).

Ocular Examination

The ocular examination is unique in medicine since most of the pathology is directly visible to the examiner; however, specialized equipment and instruments are necessary to perform a comprehensive examination. As with the general medical examination, there are multiple components to the eye examination, and they should be performed systematically.

Vision

Visual acuity

Visual acuity measures the ability to see an object at a certain distance. It is measured one eye at a time, with correction if the patient wears glasses or contact lenses, and usually recorded as a ratio comparing an individual’s results with a standard.

Distance vision using a Snellen chart at 20 feet (or 6 meters) is the most common method for recording visual acuity (Table A-1), and is denoted with VA, Va, or V and subscript of cc or sc (i.e., V_cc or V_sc) depending whether the acuity is measured with (cc) or without (sc) correction, respectively. An ocular occluder with pinholes (PH) can be used in an attempt to improve vision and estimate the eye’s best potential vision. If pinhole testing improves vision, an uncorrected refractive error or cataract is typically present. Visual acuity worse than 20 / 400 is recorded either as counting fingers (CF at the test distance; e.g., CF at 6 inches) if the patient can identify the number of fingers the examiner holds up; hand motion (HM) if the patient can identify the movement of the examiner’s hand; light perception with projection (LP and the quadrants) if the patient can identify the direction from which a light is shined into the eye; light perception without projection (LP) if the patient can determine only when a bright light is shone into the eye and not the direction the light is coming from; or no light perception (NLP) if the patient cannot perceive light from even the brightest light source. Near vision is similarly measured (monocularly with or without correction) and is denoted with N.

Table A-1

Measures of Visual Acuity: Central Visual Acuity Notations

Other types of eye charts used to measure vision include the Bailie–Lovie or Early Treatment Diabetic Retinopathy Study (ETDRS) charts used in clinical trials (vision is measured at 2 and 4 meters). On ETDRS charts, halving of the visual angle occurs every three lines as there are equal (0.1) logarithmic intervals between lines as well as consistent spacing between letters and rows, proportional to letter size. Unlike Snellen charts, the score is recorded by letter, not line. For preschool children and illiterate adults, other tests including the tumbling “E” chart, Landolt “C” chart, HOTV match test, and Allen card pictures can be used to assess visual acuity. For infants, vision is commonly evaluated by the ability to fix and follow (F&F) objects of interest or the presence of central steady maintained fixation (CSM).

Figure A-1 Eye charts for nonverbal patients or patients who cannot read English letters: (left) tumbling E chart; (right) eye chart with pictures.

Figure A-2 Patient with pinhole occluder over her left eye.

Figure A-3 Near-vision chart.

Refraction

A subjective measurement of the refractive error is performed with a phoropter or trial frame that allows the patient to decide which lens power gives the sharpest image. This test is used to determine the best spectacle-corrected visual acuity (BSCVA) and prescription for glasses. A manifest refraction is done before dilating the eyes and is denoted with M_R or M. A cycloplegic refraction is done after dilating the eyes with cycloplegic drops to prevent accommodation and is denoted with C_R or C. A cycloplegic refraction is particularly important when refracting children, hyperopes, and refractive surgery candidates, in whom a manifest refraction may not be accurate. The duochrome (red–green) test is a useful method to check the refraction for overcorrection or undercorrection. An autorefractor is an instrument that performs automated retinoscopy and measures refractive error; however, the values should be confirmed with a subjective refraction before prescribing lenses.

Figure A-4 Patient behind a phoropter undergoing manifest refraction.

Figure A-5 Patient undergoing autorefraction.

Retinoscopy

An objective measurement of the refractive error performed with a retinoscope; it is denoted with R.

Lensometer

A manual or automated instrument that measures the power of a spectacle or lens; the prescription the patient is wearing is denoted with W.

Figure A-6 A lensometer measures the power of spectacle lenses placed on the middle platform.

Potential acuity meter (PAM)

An instrument that measures the visual potential of the retina by projecting the eye chart onto the retina through corneal and /or lens opacities. This test is most commonly used to assess visual potential before cataract surgery when there is coexisting retinal pathology.

Figure A-7 Patient undergoing potential acuity meter testing. The eyechart is placed on the retina by the instrument mounted on a slit lamp. The eyechart can be focused and takes into account the patient’s refractive error.

Contrast sensitivity

Tested monocularly, usually with special charts (i.e., Pelli–Robson) having bar patterns on backgrounds with varying contrast. Reading can be plotted on a curve for different spatial frequencies.

Color vision

Tested monocularly and most commonly with Ishihara pseudoisochromatic (red–green only) or Hardy–Rand–Ritter plates. More extensive evaluation is done using Farnsworth test. Gross macular or optic nerve function can be assessed by asking the patient to identify the color of a red object such as an eyedrop bottle cap (all dilating drops have red caps). Red saturation can also be tested with the red cap by asking the patient whether the cap appears to be the same degree of brightness of red when the eyes are alternately tested.

Figure A-8 Ishihara pseudoisochromatic chart with the number 42 evident.

Stereopsis

Stereo acuity is tested binocularly and is commonly done with titmus or randot tests. The titmus test uses polarized images of a fly (patient is asked to grasp or touch the wings), animals (three rows of five cartoon animals each are pictured, and the patient is asked to touch the animal that is popping up), and circles (nine groups of four circles each are pictured, and the patient is asked to touch the circle that is popping up) of increasing difficulty to quantitate the degree of stereopsis (40 seconds of arc is normal).

Figure A-9 Three specialized tests: (A) trial frame; (B) stereo vision tests with polarized glasses; (C) Worth 4-dot test.

Figure A-10 Patient wearing polarized glasses and performing stereo acuity test; while the patient is wearing the glasses, the fly in the picture appears three-dimensional.

4-Diopter base-out prism test

This test is useful for detecting fusion or suppression in what appear to be “straight” eyes. It is an objective test that can be used on a cooperative young child who may not understand the stereo acuity test. It is also useful for the patient suspected of “faking” a negative stereo test. A 4-diopter base-out prism is placed over one eye, as the patient fixes on a distant target. A normal response is a small convergence movement by each eye. If the prism is placed over a suppressing eye, that eye will not move. A fusing eye will move toward the nose.

Worth 4-dot test

Assesses binocularity in cases of strabismus. The patient views 4 lights (1 red, 2 green, and 1 white) at distance and near while wearing special glasses with a red lens over the right eye and a green lens over the left eye. The size and location of a suppression scotoma can be determined depending on the number and pattern of lights perceived.

Figure A-11 Worth 4-dot test equipment showing patient with red–green glasses and hand-held test light.

Ocular Motility

The alignment of the eyes in primary gaze is observed, and the movement of the eyes is assessed as the patient looks in all directions of gaze by following an object that the examiner moves. Normal motility (extraocular movements) is often recorded as intact (EOMI) or full. If misalignment, gaze restriction, or nystagmus is present, then other tests are performed. Several methods are used to distinguish and measure ocular misalignment.

Figure A-12 Patient undergoing ocular motility testing. Note: Her eyes are following the pencil.

Cover tests

Assess ocular alignment by occluding an eye while the patient fixates on a target. Measurements are made for both distance and near with and without glasses.

Cover–uncover test

Distinguishes between a tropia and a phoria. One eye is covered and then uncovered. If the unoccluded eye moves when the cover is in place, a tropia is present. If the covered eye moves when the cover is removed, a phoria is present.

Figure A-13 Patient undergoing cover–uncover test to determine whether she has a phoria or tropia.

Figure A-14 Cover test for tropias and phorias. (A) For exotropia, covering the right eye drives inward movement of the left eye to take up fixation; uncovering the right eye shows recovery of fixation by the right eye and leftward movement of both eyes; covering up the left eye discloses no shift of the preferred right eye. (B) For esotropia, covering the right eye drives outward movement of the left eye to take up fixation; uncovering the right eye shows recovery of fixation by the right eye and rightward movement of both eyes; covering the left eye shows no shift of the preferred right eye. (C) For hypertropia, covering the right eye drives downward movement of the left eye to take up fixation; uncovering the right eye shows recovery of fixation by the right eye and upward movement of both eyes; covering the left eye shows no shift of the preferred right eye. (D) For exophoria, the left eye deviates outward behind a cover and returns to primary position when the cover is removed. An immediate inward movement denotes a phoria; a delayed inward movement denotes an intermittent exotropia. (Reproduced with permission from Diamond G, Eggers H: Strabismus and Pediatric Ophthalmology, 1993, London, Mosby.)

Alternate cover test (prism and cover test)

Measures the total ocular deviation (tropia and phoria). The occluder is alternately placed in front of each eye until dissociation occurs, and then hand-held prisms are held in front of an eye until no movement occurs.

Figure A-15 Patient undergoing alternate cover test in which the total ocular deviation is determined by holding prisms over the eye until no movement occurs.

Corneal light reflex tests

Assess ocular alignment by observing the relative position of the corneal light reflections from a light source directed into the patient’s eyes; can be used in patients who cannot cooperate for cover tests. The position of the corneal light reflexes can be used to measure the ocular deviation.

Hirschberg’s method

The amount of decentration of the light reflex is used to estimate ocular deviation (1 mm of decentration corresponds to 7° or 15 prism diopters [PD]). Light reflections at the pupillary margin (2 mm decentration), mid-iris (4 mm decentration), and limbus (6 mm decentration) correspond to deviations of approximately 15° or 30PD, 30° or 45PD, and 45° or 60PD, respectively.

Figure A-16 Hirschberg’s method of estimating deviation. (Reproduced with permission from von Noorden GK; Von Noorden-Maumenee’s Atlas of Strabismus, ed 3, 1977, St. Louis, Mosby.)

Modified Krimsky’s method

Prisms are placed in front of the fixating eye to center the light reflection in the deviated eye.

Figure A-17 Modified Krimsky’s method of estimating deviation. (Reproduced with permission from von Noorden GK; Von Noorden-Maumenee’s Atlas of Strabismus, ed 3, 1977, St. Louis, Mosby.)

Forced ductions

Determine whether limited ocular motility is due to a restrictive etiology. Under topical anesthesia the eye is grasped at the limbus with forceps and rotated into the deficient direction of gaze. Resistance to movement indicates restriction. The forceps should be placed on the same side of the limbus in which the eye is being moved to avoid an inadvertent corneal abrasion should the forceps slip.

Optokinetic nystagmus (OKN) testing

Assesses patients with nystagmus and other eye movement disorders. A rotating drum (or strip) with alternating black and white lines is slowly moved both horizontally and vertically in front of the patient and the resultant eye movements are observed.

Figure A-18 Patient undergoing OKN testing.

Pupils

The size, shape, and reactivity of the pupils are assessed while the patient fixates on a distant target. Both the direct and consensual responses are observed. The swinging flashlight test is done to identify a relative afferent pupillary defect (see RAPD in Chapter 7), particularly if anisocoria or poor reaction to light is present. If the pupils react to light, then they will react to accommodation, so this does not need to be tested; however, if one or both pupils do not react to light, then the reaction to accommodation should be assessed since some conditions may cause light-near dissociation.

The reactivity of each pupil is graded on a scale of 1 + (sluggish) to 4 + (brisk). Normal pupils should be equal, round, and briskly reactive to light. The most common abbreviation for denoting this pupillary response is “pupils equal round and reactive to light” (PERRL or PERRLA if accommodation is also tested). A preferred method that provides more information is to note the size of the pupils before and after the light stimulus is applied (i.e., P 4 → 2 OU). If anisocoria is present, the pupils should be measured in both normal lighting conditions and dim conditions (mesopic or scotopic).

Visual Fields

Confrontation visual fields are evaluated monocularly with the patient and examiner sitting opposite one another and looking into the examiner’s opposite eye (used as a control) while being asked to identify the number of fingers presented or the movement of a finger in each quadrant. Normal fields are recorded as visual fields full to confrontation (VFFC or VF full).

Figure A-19 Patient undergoing confrontation visual field testing.

Amsler grid

A 10 cm × 10 cm grid composed of 5 mm squares that evaluates the central 10° of the visual field. This test is most commonly used to assess central visual distortion in patients with age-related macular degeneration and other macular pathology.

Figure A-20 Amsler grid.

Tangent screen

A manual test that is performed with the patient seated 1 m in front of a 2 m × 2 m square black cloth over which the examiner presents test objects (spheres of various size and color).

Goldmann visual field

A manually operated machine used to perform static and kinetic perimetry centrally and peripherally.

Figure A-21 Kinetic and static perimetry. (Reproduced with permission from Bajandas FJ, Kline LB: Neuro-Ophthalmology Review Manual, ed 3, 2004, Thorofare, NJ, Slack.)

Figure A-22 Patient undergoing Goldmann visual field examination.

Figure A-23 Normal (A) Goldmann and (B) Humphrey visual field.

Humphrey visual field

A computerized static perimetry test with various programs to screen for and evaluate glaucomatous, neurologic, and lid-induced visual field defects.

External Examination

Orbit, eyelid, and lacrimal structures are evaluated for symmetry, position, and any abnormalities. Palpation and auscultation are performed when indicated.

Exophthalmometry

Measurement of the distance the corneal apex protrudes from the lateral orbital rim to assess for proptosis or enophthalmos. The exophthalmometer is adjusted to rest against the lateral orbital rims, and with the patient looking in primary gaze, the level of each corneal apex is viewed in the exophthalmometer mirrors; these measurements are recorded along with the base number (width of the orbital rims).

Figure A-24 Patient undergoing exophthalmometry test to measure for proptosis or enophthalmos.

Schirmer’s test

Special strips of 5 × 35 mm Whatman #41 filter paper are placed in the lower eyelids to absorb tears and measure tear production to evaluate dry eyes (see Dry Eye Disease in Chapter 4).

Figure A-25 Patient undergoing Schirmer’s testing for dry eyes. This patient’s tears have wet the strips sufficiently, indicating that she does not have dry eyes.

Jones’ dye tests

Two tests that evaluate lacrimal drainage obstruction (see Nasolacrimal Duct Obstruction in Chapter 3).

Other cranial nerve examination

CN5 is tested to assess facial and corneal sensation, and CN7 is tested to assess facial movement including eyelid closure, when warranted.

Slit-Lamp Examination (SLE)

This specialized biomicroscope allows detailed examination of the eye. The height, width, and angle of the light beam can all be controlled, and various filters can be changed to enhance visualization. A thin beam directed through the clear ocular media (cornea, anterior chamber, lens, and vitreous) acts as a scalpel of light illuminating a cross-sectional slice of optical tissue. This property of the slit-lamp allows precise localization of pathology. The technique of retroillumination (coaxial alignment of the light beam with the oculars) uses the red reflex from the retina to backlight the cornea and lens, making some abnormalities more easily visible. Furthermore, anterior segment lesions can be accurately measured by recording the height of the slit-beam from the millimeter scale on the control knob. Although the posterior segment can be evaluated with the aid of additional lenses, the SLE typically focuses on the anterior segment.

Portable, hand-held, slit-lamp devices facilitate examination at the bedside. If a slit-lamp instrument is not available, a penlight examination can be done with a magnifying lens to briefly assess the anterior segment. Similarly, a direct ophthalmoscope or indirect ophthalmoscope and lens can also be focused on the anterior segment structures for examination.

Figure A-26 Patient undergoing slit-lamp examination.

Components of the slit-lamp examination

Lids, lashes, and lacrimal glands

The lids, lashes, puncta, and Meibomian gland orifices are inspected. The medial canthus or lid margin can be palpated to express discharge or secretions from the inferior punctum or Meibomian glands, respectively. The lacrimal gland can also be inspected and palpated.

Conjunctiva and sclera

The patient is asked to look in the horizontal and vertical directions to observe the entire bulbar conjunctiva, and the lids are everted to observe the tarsal conjunctival surface. The caruncle and plica semilunaris are also inspected. The upper eyelid can be double everted to evaluate the superior fornix, and a moistened cotton-tipped applicator can be used to sweep the fornix to remove suspected foreign bodies.

Figure A-27 Technique for everting the upper eyelid.

Cornea

All five layers of the cornea are inspected. The tear film is evaluated for break-up time and height of the meniscus. The cobalt-blue filter allows better visualization of corneal iron lines.

Anterior chamber

The anterior chamber is evaluated for depth – graded on a scale from 1 + (shallow) to 4 + (deep) – and the presence of cells and flare (see Chapter 6). Normally, the AC is deep and quiet (D&Q).

Iris and lens

The iris and lens are inspected. The lens is better evaluated after pupillary dilation. If the eye is pseudophakic, the position and stability of the intraocular lens implant are noted, and the condition of the posterior capsule is assessed. The anterior vitreous (AV) can also be observed without the use of additional lenses. For aphakic eyes, the integrity of the anterior hyaloid face is evaluated, and any vitreous prolapse into the AC or strands to anterior structures is noted.

Dyes

Fluorescein, rose bengal, and lissamine green can be used to evaluate the health and integrity of the conjunctival and corneal epithelium. The integrity of wounds is assessed with the Seidel test (see Laceration in Chapter 5).

Gonioscopy

Evaluation of the anterior chamber angle structures with special mirrored contact lenses that are placed on the cornea. Various grading systems exist to specify the degree to which the angle is open. Indentation gonioscopy is used to determine whether angle closure is due to apposition (opens with indentation of the central cornea, which pushes aqueous peripherally) or synechiae (does not open with indentation).

Figure A-28 Goldmann gonioscopy lens.

Figure A-29 Shaffer’s angle grading system. (Reproduced with permission from Fran M, Smith J, Doyle W: Clinical examination of glaucoma. In: Yanoff M, Duker JS [eds]: Ophthalmology, ed 2, 2004, St. Louis, Mosby.)

Fundus contact and noncontact lenses

Numerous lenses can be used to examine the retina and optic nerve. Although performed with a slit-lamp, these findings are recorded as part of the fundus examination (see below).

Tonometry

Various instruments can be used to measure the intraocular pressure (IOP). Most commonly, IOP is measured as part of the slit-lamp examination (SLE) with the Goldmann applanation tonometer (a biprism that creates optical doubling), which is attached to the slit-lamp. Topical anesthetic drops and fluorescein drops (either individually or in a combination drop) are instilled into the eye, the tonometer head is illuminated with a broad beam and cobalt-blue filter, the tip contacts the cornea, the dial is adjusted until the mirror-image semicircular mires slightly overlap so that their inner margins just touch each other, and the pressure measurement in mmHg is obtained by multiplying the dial reading by 10 (i.e., “2” equals 20 mmHg). If marked corneal astigmatism exists, to obtain an accurate reading the tonometer tip must be rotated so that the graduation marking corresponding to the flattest corneal meridian is aligned with the red mark on the tip holder. Central corneal thickness also affects pressure readings. It is important to record the time when the pressure is measured. If a slit-lamp is not available, portable hand-held devices such as the Tono-Pen, Perkins, or Shiotz tonometers can be used. Estimating IOP by digital palpation (finger tension) is highly inaccurate.