Anterior chamber angle

Gonioscopy anterior chamber angles will be closed ... 

Gonioscopy Examination of the anterior chamber angle of the eye. A gonioprism or Goldman lens is used to perform gonioscopic evaluation. 

Gonioscopy Because pupil dilation may precipitate an acute attack of narrow-angle glaucoma, evaluate anterior chamber angle by gonioscopy prior to beginning therapy. 

Both mydriasis and cycloplegia are useful in ophthalmology. They are also potentially hazardous, since acute glaucoma may be induced in patients with a narrow anterior chamber angle. 

Cycloplegia is reserved for a limited number of conditions (e g., suspected latent hyperopia, accommodative esotropia, amblyopia treatment). Hyperopic patients may have shallow anterior chamber angles that require... 

Figure 5-1 Example of informed consent document for dilation of the pupil when the patient has a narrow anterior chamber angle.

Among the cycloplegics most frequently used are cycfopentolate and atropine. Because of their potential side effects, a careful history and assessment of the anterior chamber angle are necessary before use. Selection of the appropriate agent is also important (see Chapter 21). If there is a risk of angle closme, this risk must be communicated to patients, and informed consent should be obtained before the drug is administered. 

Cockburn DM. Prevalence and significance of narrow anterior chamber angles in optometric practice. Am J Optom Physiol Opt 1981 58 171-175. 

Hydroxyamphetamine has little if any effect on accommodation or on the refractive state. It also does not raise lOP in eyes with open anterior chamber angles. 

In addition, most eyes with primary open-angle glaucoma treated with pilocarpine demonstrate narrowing of the anterior chamber angle and thickening of the crystalline lens after each instillation of the drug. 

Acute angle-closure glaucoma is a rare but well-recognized complication of mydriatic use. Because the risk of such a complication is greatest in eyes with shallow anterior chambers, the practitioner should evaluate the anterior chamber angle before instilling any mydriatic. 

Extremely narrow or closed anterior chamber angles History suggesting angle-closure glaucoma, without surgical or laser intervention ... 

Slit-lamp evaluation, with particular attention to the cornea, anterior chamber depth, and an estimation of the anterior chamber angle by shadow test or van Herick s classification... 

Pupil distortion may be related to the type and location of lOL implants. Some of the early iris-fixated and iris-plane lenses often caused square pupils, and some of the early anterior chamber lOLs, such as the Choyce lens, caused the pupil to be stretched in an oval appearance. The older lenses were also more likely to irritate the iris and anterior chamber angle, causing chronic low-grade iritis. Chronic iritis, in turn, resulted in iris atrophy, synechiae formation, and pupil distortion. These lenses have been replaced by posterior chamber lOLs inserted into the capsular bag. Dislocation of a posterior lOL is rare but possible (Figure 30-7). 

It seems likely that manufacturers will develop archived cUnical databases in future permutations of this technology. This would permit comparison of parameters such as the anterior chamber depth and configuration of the anterior chamber angle with an internal database. ProbabiUty analysis could be generated to determine the extent of deviation from a norm or the risk of angle closure. 

Direct Ophthalmoscopy. The direct ophthalmoscope is perhaps an imdemtilized instmment in the assessment of glaucoma. It can provide information regarding pupil function, an estimation of the anterior chamber angle depth, spherical refractive error of the patient, presence of media opacity, and a magnified view of the optic nerve... 

Neovascular glaucoma is a condition maiked by new blood vessel proliferation on the iris and in the anterior chamber angle usually as a result of retinal or anterior segment ischemia/hypoxia. Neovascularization of the iris usually appears first on the surfece of the iris adjacent to the pupillary border.These vessels are fine in caliber and may have aneurysm-like outpouchings. Gonioscopic evaluation may reveal vessels in the anterior chamber angle even in the absence of iris vessels. 

In most cases of glaucoma associated with inflammation, the anterior chamber angle is open, and the increase in lOP results from direct involvement of the trabecular meshwork as a consequence of local inflammation (e.g., secondary trabeculitis) or preexisting outflow anomalies exacerbated by perilimbal inflammation elevating episcleral venous pressure. Less commonly local inflammation causes an increase in lOP as result of a secondary angle closure (Box 34-7). 

Among the drugs most commonly implicated are the sulfonamides. Two cases of transient myopia associated with oral sulfonamides were described in which there was reduced accommodation, shallow anterior chamber angles, and moderate mydriasis. Chemosis occurred in one case. A 23-year-old woman was described who had 4.00D of increased myopia in one eye and 3.00D of increase in the fellow eye after the use of oral sulfonamides. Vaginal absorption of sulfonamides can also lead to myopia. A patient was reported with 1.00 to 1.50D of myopia after use of a vaginal sulfonamide suppository and another patient with 7.00D of induced myopia after use of a sulfonamide vaginal cream. 

Diuretic agents can cause myopia. Transient myopia was associated with perimacular edema apparently caused from the use of 100 mg of hydrochlorothiazide. The drug induced approximately 3.00D of myopia, which resolved within 3 days. Carbonic anhydrase inhibitors are also known to cause myopia. A case of transient myopia associated with acetazolamide was reported, in which there was also narrowing of the anterior chamber angle. 

Anterior chamber angle includes all of the following structures except ... 

Primary open-angle glaucoma (POAG) is a multifactorial chronic optic neuropathy with a characteristic acquired loss of optic nerve fibers. Cupping and atrophy of the optic disc occur in the absence of other known causes. Such damage develops in the presence of open anterior chamber angles. It produces characteristic visual field abnormalities. lOP is too high for the continued health of the eye. 

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