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A. Symptoms of cataract formation

1. Decreased vision. Cataracts cause painless progressive decrease in vision. Clinically significant cataracts cause adecrease in distance or near visual acuity. Posterior subcapsular cataracts of even mild degree can reduce visual acuitysubstantially. Nuclear sclerotic cataracts cause image blur at distance but not at near. Image blur occurs when the lens

loses its ability to differentiate resolve! separate and distinct ob"ect points. #hen this occurs$ near visual tas%s$ such asreading and sewing$ become more difficult. &any older patients may tolerate considerable reductions in distance acuityif their night driving is minimal$ but they may not be as tolerant of a blur that interferes with their indoor activities.

'. (lare. )ne of the symptomatic manifestations of light scattering is glare. #hen a patient loo%s at a point source oflight$ the diffusion of bright white and colored light around it drastically reduces visual acuity. *he effect is a%in to

loo%ing at automobile headlights at night through a dirty windshield. Posterior subcapsular opacification is responsiblefor much of the glare.

+. Distortion. Cataracts may ma%e straight edges appear wavy or curved. *hey may even lead to image duplicationmonocular diplopia!. If a patient complains of double vision$ it is essential to determine if the diplopia is binocular ormonocular. If monocular$ the e,aminer is usually dealing with corneal$ lenticular$ or macular disease.

-. Altered color perception. *he yellowing of the lens nucleus steadily increases with age. Artists with significantnuclear sclerosis may render ob"ects more brown or more yellow than they actually are.

. /nilateral cataract. A cataract may occur in only one eye or may mature more rapidly in one eye than in the other.

/nless the patient is in the habit of chec%ing the acuity of each eye$ he or she may not be aware of the presence of adense cataract in one eye. It is not uncommon for a patient to claim that the vision in the cataractous eye was lostprecipitously. 0ecause cataracts rarely mature precipitously$ it is more li%ely that the slowly evolving lens opacity wasunrecognied until the patient happened to test his or her monocular acuity.

2. 0ehavioral changes

a. Children with congenital$ traumatic$ or metabolic cataracts may not verbalie their visual handicap. 0ehavioralchanges indicative of a loss of acuity or binocular vision may alert the parents or teachers to the presence of avisual problem. Inability to see the blac%board or read with one eye may be one such symptom3 loss of accuratedepth perception$ e.g.$ the inability to catch or hit a ball or to pour water from a pitcher into a glass$ may be another.

b. Prepresbyopic adults. Difficulty with night driving is fre4uently an early sign of cataract.

c. Presbyopic adults. 5re4uently$ maturation of nuclear cataracts is associated with the return of clear near vision asthe result of increasing myopia secondary to the higher refractive power of the rounder$ harder nuclear scleroticlens. 6eading glasses or bifocals are no longer needed. *his change is called 7second sight.8 /nfortunately$ theimprovement in near vision is only temporary as the nuclear one becomes more opa4ue.

0. Signs of cataract formation1. 6educed visual acuity. Although it is not part of the usual general physical e,amination$ the measurement of visualacuity will alert the e,aminer to the presence of cataract as well as other ocular disorders. *he e,aminer should alwaysin4uire about monocular acuity when conducting a review of systems.'. 9enticular opacification. :,amination of the red refle, with the direct ophthalmoscope set on ; blac%! D at

appro,imately '< cm from the patient fre4uently will reveal a blac% lens opacity against the reddish=orange hue of therefle,. *his is an e,tremely sensitive method of detecting cataractous change. If on upgae the opacity appears to movedown$ the opacity is in the posterior half of the lens3 if the opacity moves up with upgae$ it is located in the anteriorhalf of the lens or in the cornea.+. 9eu%o%oria. *he white pupil is seen in mature cataracts3 in certain immature cataracts$ whitish patches are seen in the

pupillary one$ the result of foci of light scattering$ located in the anterior subcapsular or cortical one.

C. Diagnostic tests and spectacle correction for cataract1. /ncorrected and spectacle=corrected Snellen visual acuity. Distant and near acuity with and without the appropriate

glasses should be tested. Some patients with cataracts complain of poor visual function despite good Snellen visual

acuity. Snellen charts measure high=contrast visual acuity. Cataracts can cause decreased appreciation of contrast$leading to sub"ective visual dysfunction. Snellen visual acuity in a brightly lit room versus a dar% room may besubstantially worse secondary to glare.

'. Non=Snellen acuity. *ests of contrast sensitivity may be used to ob"ectively document sub"ective decrease incontrast$ although they have yet to be widely standardied for this purpose. Cataracts$ especially posterior

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subcapsular and cortical$ may cause debilitating glare. Several readily available instruments can document theeffect of glare on visual acuity$ e.g.$ brightness acuity testing. Confrontation visual fields and (oldmann andautomated visual field testing may be valuable to evaluate the degree of preoperative visual field loss. Potentialacuity meter testing can be helpful in evaluating the lenticular contribution to visual loss. Similarly$ laserinterferometry is predictive of final visual acuity in moderately dense cataracts.

+. 5lashlight e,amination of lens and pupil. *he direct and consensual pupillary responses are not affected by lensopacities if a bright light is used3 if a dim flashlight is used$ the responses may be less pronounced whenilluminating the eye in the presence of a dense cataract. A flashlight may also render anterior lens opacities morevisible to the e,aminer if pupil sie is not reduced e,cessively.

-. Direct ophthalmoscopy. #ith the pupil dilated$ nuclear cataracts often appear as a lens within a lens when viewed

against the red refle, with a ; to ;1< D lens.

. Slitlamp biomicroscopy allows the most detailed e,amination of the anterior part of the eye. *he e,tent$ density$type$ and location of the cataract can be easily determined. Slitlamp e,amination is also helpful in determining theposition of the lens and the integrity of the onular fibers. :,cessive distance between the lens and the pupillarymargin may indicate lens sublu,ation. Slitlamp biomicroscopy may have limitations$ especially in detecting oil

droplet cataracts$ which may be easier to detect using the direct ophthalmoscope through the 1< D lens.

2. 6efraction and retinoscopy. &yopia induced by the early stages of nuclear cataract formation can be detected byroutine refraction. Patients may be well corrected for years with a stronger myopic distance lens and reading add.6etinoscopy will reveal the abnormal refle,es associated with lenticonus$ a condition in which the anterior or

posterior surface of the lens or both! is e,cessively conve, or conical.

>. 5undus evaluation. 0oth the direct and indirect ophthalmoscope can be used to evaluate the anatomic integrity ofthe posterior segment. Dilated fundus e,amination is necessary to evaluate the macula$ optic nerves$ vitreous$retinal vessels$ and retinal periphery. Attention to macular degeneration$ diabetic retinopathy$ macular edema$retinal ischemia$ vitreoretinal traction$ neovasculariation$ optic nerve pallor$ e,tensive cupping$ and posteriorcapsular ruptures is important because these conditions may limit visual rehabilitation after cataract surgery.

?. A=scan and 0=scan ultrasonography are techni4ues for measuring the thic%ness and location of a cataract. A=scanultrasound techni4ues to measure the eye@s a,ial length paired with %eratometric measurement of corneal curvatureallow precise calculation of appropriate intraocular lens I)9! power$ thus minimiing postoperative sphericalrefractive error. 0=scan techni4ues are particularly useful in evaluating partial or total dislocation of the lens$ andalso provide a means of detecting abnormalities in the posterior half of the eye in the presence of a very dense

cataract that precludes direct visualiation. Some secondary cataracts form in response to posterior segment tumorsor inflammation$ thereby necessitating ultrasonography to ascertain the anatomic state of the eye behind the lenssee Chapter 1$ sec. III..!.

BI. &edical treatment of cataract

A. Dietary factors. :pidemiologic studies have recently indicated that patients with diets high in the antio,idantcarotenoid alpha carotene had a notably lower incidence of nuclear cataract$ those high in the carotenoid lycopene werelowest in cortical cataract$ and those high in the carotenoids lutein and possibly ea,anthin were lowest in posteriorsubcapsular cataract. Bitamins C and : had no notable effect.0. &ydriatics. *he patient with a small a,ial cataract may occasionally benefit from pupillary dilation mydriasis!3 thisallows the clear$ para,ial lens to participate in light transmission$ image formation$ and focusing$ eliminating the glare

and blur caused by these small central cataracts. Phenylephrine '.$ one drop bid in the affected eye$ may clarifyvision. In the hypertensive patient$ the use of a short=acting$ mydriatic=cycloplegic drug such as tropicamide 1 orcyclopentolate 1 will e,acerbate hypertension.

C. Diabetes

1. Age=related cataracts$ as stated earlier$ are widely believed to occur more fre4uently and mature more rapidly indiabetics. ust as careful control of blood sugar levels can minimie the troublesome changes in refractive error thatoccur in patients with poorly controlled diabetes$ some mild cataracts can be reversed through diabetic control.Advanced cataracts are not benefited by better control of diabetes.'. Aldose reductase inhibitors have been used successfully in animals to prevent 7sugar cataract8 diabetic andgalactosemic! formation3 such drugs may be beneficial in human diabetics. 0loc%ing the conversion of glucose to

sorbitol by aldose reductase might delay or prevent the adverse osmotic stress resulting from the intracellularaccumulation of sorbitol$ a sugar alcohol.

D. 6emoving cataractogenic agents. Irradiation infrared and ,=ray radiation! as well as drugs corticosteroids$phenothiaines$ cholinesterase inhibitors$ and others! can cause cataracts. Conversely$ their removal may delay orprevent further progression of the cataract. Any drug or agent with %nown cataractogenic properties should be used as

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briefly$ at as low a dose as possible$ or both. )phthalmologic evaluation before and during treatment can alert thephysician to signs of cataract formation.

BII. Surgical treatment of cataractA. *iming of surgery

1. Bisual considerations. *he mere presence of a cataract is insufficient reason for its removalE It is important toestablish the patient@s specific visual needs before underta%ing surgery. If the cataract is uniocular$ surgery may bedelayed until the cataract is mature$ as long as visual function in the fellow eye is sufficient for the patient@s needs andthe patient does not need stereoscopic vision. If bilateral cataracts are present$ e,traction of the cataract from the eye

with the worse visual acuity may be done when the patient regards the visual handicap as a significant deterrent to themaintenance of his or her usual lifestyle.

0. Preoperative evaluation and considerations

1. *he preoperative ophthalmologic evaluation should include a complete e,amination to rule out comorbid conditions$such as longstanding amblyopia$ pseudoe,foliation$ retinal tears or holes$ macular lesions$ or optic nerve abnormalities

that may affect the visual or surgical outcome. An accurate refraction of both eyes$ measurement of corneal refractivepower with a %eratometer$ and measurement of a,ial length with an A=scan ultrasound are all necessary to calculate theappropriate I)9 power. Some surgeons measure macular acuity using devices that pro"ect either Snellen letters orgratings onto the macula through a relatively clear part of the lens potential acuity meter!. *hese measurements givethe surgeon and patient an indication of the visual acuity that can be obtained postoperatively$ but they are not

foolproof. *hese tests tend to underestimate postoperative visual acuity in some situations$ while overestimating visualacuity in some macular diseases.

'. Preoperative medical evaluation. :ach patient should be evaluated by an internist or general practitioner beforesurgery for any conditions that may affect the patient@s surgical or postsurgical course. *he necessary testing depends onthe patient@s age and prior medical history.

+. Preparation for surgery should include a full e,planation of the potential ris%s and benefits of proposed surgery andanesthesia$ as well as the techni4ue for administering eye drops and ointments and other postoperative care. Anyblepharitis$ dacryocystitis$ or other ocular surface disease should be treated and resolved before proceeding withintraocular surgery.

-. 0oth outpatient and inpatient surgical facilities are used for cataract surgery$ with the latter reserved for patients at

ris% for medical complications. #ell=designed$ certified outpatient surgical facilities offer the patient the briefestpossible surgical e,perience and reduce to a minimum the disruption of the patient@s normal living routine. Suchfacilities offer the surgeon an opportunity to deliver state=of=the=art surgical care in an efficient outpatient environmentat minimal cost.

C. Preoperative medications

1. Mydriasis. 5or planned e,tracapsular cataract e,traction :CC:! and phacoemulsification$ it is crucial that the pupilbe widely dilated throughout most of the procedure. *his is most often achieved with a preoperative combination of anadrenergic agent such as phenylephrine!$ an anticholinergic agent such as cyclopentolate or tropicamide!$ and acycloo,ygenase inhibitor such as flurbiprofen!. *he cycloo,ygenase inhibitor is believed to contribute to maintainingand preventing formation of intraoperative mydriasis. Intraoperative mydriasis may also be maintained with the use ofdilute epinephrine in the irrigating solution.

2. Anesthesia options.Cataract e,traction may be performed under local$ topical$ or general anesthesia. 9ocalanesthesia minimies the ris% of wound rupture$ a complication fre4uently associated with coughing during e,tubationand postoperative nausea and vomiting. *he use of 1E1 mi,ed ' to - ,ylocaine and bupivacaine in facial andperibulbar or retrobulbar bloc%s achieves rapid anesthesia$ a%inesia$ and postoperative analgesia for several hours. Careto avoid intravascular in"ections of anesthetic is essential$ because refractory cardiopulmonary arrest may result from an

inadvertent intravenous or intraarterial in"ection. &any patients e,press dread of the facial and retrobulbar in"ections3proper preoperative sedation and good rapport with the surgeon ma%e them 4uite tolerable.*opical anesthesia$ in con"unction with intravenous sedation and clear corneal incisions$ has been used with increasingfre4uency in very cooperative patients and does not carry the ris%s of local anesthesia. *his is becoming the mostcommonly used approach for managing uncomplicated soft cataracts. It permits very early postoperative use of the eye$because there is no lid ptosis$ diplopia$ or amaurosis. Although topical anesthesia for cataract surgery is a relatively new

approach$ it will be some time before safety comparable to retro= or peribulbar techni4ues can be demonstrated inpatients with dense nuclei. Patients who are e,tremely apprehensive$ deaf$ mentally retarded$ unstable$ or cannotcommunicate well with the surgeon are discouraged from having topical anesthesia.3. Intraocular pressure (IOP) lowering. Preoperative I)P reduction can prevent such operative complications asvitreous loss$ e,pulsive choroidal hemorrhage$ and shallowing of the anterior chamber. *his can be accomplished bymechanical pressure digital massage or onan balloon! or osmotic means intravenous mannitol!.

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4. Preoperative preppingFantibiosis is designed to prevent postoperative endophthalmitis$ a condition that isdevastating but rare. &any surgeons prescribe a topical antibiotic such as tobramycin preoperatively to eradicatecon"unctival bacterial flora. &ost surgeons prepare the lids and facial s%in with 1.'!. *his techni4ue is designed to remove the opa4ue portions of the lens without disturbing the

integrity of the posterior capsule and anterior vitreous face. Compared to ICC:$ there is a significantly lower incidenceof postoperative cystoid macular edema C&:! and retinal detachment$ improved prognosis of subse4uent glaucomafiltering surgery or corneal transplantation$ reduced incidence of vitreocorneal touch and bullous %eratopathy$ andreduced secondary rubeosis in diabetics. In :CC:$ the anterior capsule is opened widely$ the nucleus e,pressed througha G= to 1