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242 Color Atlas of Ophthalm ology

Differential Diagnosis

En dogen ou s en doph th alm it is, in t raocu lar foreign body, vit reou s h em orrh age, glaucom a (len s p ar t icle, ph acolyt ic, ph acom orph ic, an d uveit is), an d vit reou s w ick syn drom e

Management

Obt ain vit reou s, aqu eou s sam p les an d conju n ct ival cu lt u res for m icrobiological id en t ificat ion of t h e offen d ing organ ism . B-scan is d on e to con fir m t h e d iagn osis. Th e resu lt s of an en d op h t h alm it is vit rectom y st u dy d em on st rated n o d ifferen ce in fin al visu al ou tcom es in p at ien t s w h o u n d er w en t in it ial in t raocu lar an t ibiot ic inject ion (vit reou s t ap ) or im m ed iate p ars p lan a vit rectom y (vit rectom y) if p re - sen t ing visu al acu it y w as bet ter t h an ligh t p ercept ion . How ever, in p at ien t s p resen t ing w it h ligh t p ercept ion vision , t h ose w h o u n d er w en t in it ial VIT w ere t h ree t im es m ore likely to ach ieve 20/40 vision , t w ice as likely to m ain t ain 20/100 vision , an d h ad a n early 50% red u ct ion in t h e r isk of severe visu al loss (<5/200), com p ared w it h p at ien t s w h o u n d er w en t TAP. No lon g-ter m d ifferen ce occu r red in m ed ia clar it y bet w een t reat m en t grou p s. In t raven ou s an t ibiot ics h ad n o effect on eit h er t reat m en t ou tcom e.

Van com ycin h as been sh ow n effect ive again st greater th an 99%of gram -posit ive en doph th alm it is isolates. Th e am in oglycoside am ikacin (0.4 m g in 0.1 m L) is u seful for gram -n egat ive coverage. Approxim ately 90% of gram -n egat ive isolates are su scept ible to th is agen t . Ceft azidim e is a reason able altern at ive for gram -n egat ive coverage. Th e use of in t ravit real dexam eth ason e in th e t reat m en t of acute postoperat ive en doph th alm it is rem ain s con t roversial. In ch ron ic postoperat ive en doph th alm it is from Propionibacterium acnes, in t raocu lar van com ycin alon e h as been associated w ith h igh rates of persisten t in flam m at ion .

Th e en doph th alm it is vit rectom y st u dy recom m en ds rapid in ter ven t ion w ith su rger y for pat ien t s w ith severe vision loss on presen tat ion .

Intraocular Lens Opacification

It h as been m ore th an 50 years sin ce Harold Ridley’s first im plan t , an d th e cata- ract-IOL procedu re h as reach ed an ext raordin arily h igh level of qu alit y an d perfor- m an ce. How ever, com p licat ion s su ch as IOL opacificat ion do occu r (Fig. 7.30A,B).

A B

Fig. 7.30 (A) Opacified intraocular lens. (B) Opacified intraocular lens explanted.

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Presentation

Th e opacit ies of th e IOL opt ics m ay st ar t as scat tered w h ite-brow n spot s w ith in th e su bst an ce of th e IOL opt ic an d rem ain stable or slow ly progressive. Som e m ay gradu ally in crease in in ten sit y an d n um bers, even t u ally reach ing a poin t w h ere a visu al acuit y loss m ay n ecessitate rem oval or exch ange of th e IOL. In addit ion to visu al loss, th e repor ted sym ptom s in clu ded decrease in con t rast sen sit ivit y an d variou s visu al dist u rban ces an d aberrat ion s, in clu ding glare. In th e early stages th ere w as usually n o effect on Sn ellen visu al acu it y, bu t a gradual decrease of visu al acu it y w as n oted in th e late st age of th e process.

Differential Diagnosis

Cat aract

Management

If n ecessar y, on e sh ould explan t an d rem ove th e opacified IOL an d replace it w ith a n ew on e.

8 Glaucoma 245

Fig . 8.1 Normal anatomy and fluid dynamics compared with the anatomy and fluid dynamics of a glaucoma patient. (A) The normal flow of aqueous humor through the trabecular meshwork (T) to the floor (F) of the Schlemm canal (SC). Active transport of the aqueous humor occurs through the norm al endothelium (E) to the lumen of the canal. It is then drained through small openings in the external wall or roof of the Schlemm canal (SC), into scleral collector channels and then into capillaries and veins within the subconjunctival tissues. (B) In a diseased eye with open-angle glaucom a, the endothelium

(E) of the Schlem m canal is more resistant to aqueous outflow, as is the immediately adjacent trabecular meshwork. This is the site of highest resistance to aqueous flow. Passage of aqueous humor is very slow, resulting in the increased intraocular pressure of glaucoma. (Inset) Anatomically, the Schlemm canal (SC) is located slightly behind the

lim bus. (Courtesy of Highlights of Ophthalmology, “Innovations in the Glaucomas: Etiology, Diagnosis and Management,” English Edition, 2002. Eds: Benjamin F. Boyd, MD, FACS; Maurice H. Lunt z, MD, FACS; Co-Editor: Sam uel Boyd, MD.)

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Normal-Tension (or Low -Tension) Glaucoma

Th is is th e con dit ion in w h ich opt ic n er ve h ead loss, loss of n er ve fiber layer, an d th e visual field defect s are th e sam e as seen in ch ron ic glaucom a, bu t th ere is n o rise in IOP. Norm al-ten sion glau com a (NTG) form s 16%of all th e glau com as.

Presentation

Pat ien ts are m ostly asym ptom at ic. Occasion ally th e pat ien t presen ts w ith scotom a. Th ere m ay be an associated h istor y of episodes of isch em ic opt ic n europathy, n eu - rological sym ptom s, m igrain e, or Rayn au d disease.

A

Fig. 8.2 (A) Posterior segment optical coherence tomography (OCT) showing optic nerve head analysis in a patient with normal-tension glaucoma and advanced glaucomatous cupping.

8 Glaucoma 247

IOPs are recorded as n orm al. Th e opt ic disk is t ypically large in NTG. Cu pping is p ropor t ion ally larger th an visual-field loss. A sloping n euroret in al rim edge w ith sh allow cu p, h igh er in ciden ce of opt ic disk pit associated w ith it , peripap illar y at rophy, opt ic disk h em orrh ages, steeper an d deep er visual-field defect s close to fixat ion , a posit ive fam ily h istor y, m yopia, n oct u rn al hypoten sion , an d a h istor y of carot id ar ter y disease are som e of th e associated feat ures (Figs. 8.2A,B).

Differential Diagnosis

In cludes cases w ith in term it ten t pressu re elevat ion or diu rn al variat ion s in pri- m ar y open -angle glaucom a (POAG), pat ien t s w ith long-term flu ct u at ion s in pressu re elevat ion s th at h ave been m asked by system ic m edicat ion s such as β-block- ers; oth er n onglaucom atous opt ic n europathy; congen ital abn orm alit ies of th e opt ic n er ve h ead

B

Fig . 8.2 (Continued) (B) Posterior segment OCT showing retinal nerve fiber layer analysis in a patient with bilateral advanced normal-tension glaucoma.

248 Color Atlas of Ophthalm ology

Management

A com plete ocular an d system ic h istor y is im por tan t . Histor y of drug in t ake, vascular problem s, n eu rological problem s, an d cardiological problem s m u st be recorded . Carefu l ocular exam in at ion w ith stereoscopic opt ic n er ve h ead evaluat ion , periph eral fu n dus exam in at ion , an d gon ioscopic an d field exam in at ion m ust be don e.

A 20 to 25%redu ct ion in th e IOP is aim ed in early an d m oderate field ch anges, an d it sh ou ld be less th an 25% in pat ien ts w ith severe field ch anges. Miot ics, α -2 agon ist , β-blockers, dorzolam ide an d lat an oprost are good opt ion s to redu ce IOP. Calcium ch an n el blockers an d n europrotect ion play a prom in en t role in th e m an - agem en t of NTG. Filt rat ion surger y is an opt ion in advan ced field defects.

Secondary Open-Angle Glaucoma

Secon dar y open -angle glau com a is OAG th at occu rs secon dar y to som e oth er cau se.

Pigmentary Dispersion Glaucoma

Pigm en t dispersion syn drom e (PDS) is gen erally an asym ptom at ic disorder discovered du ring rout in e oph th alm ic evaluat ion . Pigm en t ar y glaucom a is a sequ ela of PDS. Developm en tal abn orm alit ies of th e iris pigm en t epith eliu m are th e fun - dam en t al defect respon sible for th e pigm en t dispersion . Th e con dit ion is seen in a relat ively younger age grou p an d is m ore com m on in m en th an in w om en . Myopia an d a deep an terior ch am ber are th e risk factors for th e developm en t of PDS. It is com m on in person s of Europ ean descen t .

Presentation

Th e con dit ion is diagn osed in ciden t ally in m ost of th e cases. Few pat ien t s com plain of colored h alos an d sm oky vision in th e dim ligh t con dit ion s an d after vigorous physical exercise. Pat ien t s h ave a raised IOP, defect ive fields, an d opt ic disk cu p - ping. Oth er associated fin dings in clu de Kruken berg spin dle, raised cen t ral corn eal th ickn ess, iris t ran sillum in at ion defect , con cave periph eral iris, an isocoria, ring of pigm en t at ion over th e periph eral su rface of th e len s, an d a h igh ly pigm en ted t rabecu lar m esh w ork (Fig. 8.3).

Differential Diagnosis

Pseu doexfoliat ive glau com a

Management

Pat ien ts w ith PDS are alw ays con sidered as glaucom a su spect s an d IOP sp ikes, visu al fields, cu pping, an d gon ioscopy are ch ecked an n u ally. Myopic pat ien t s w ith PDS h ave to be ch ecked for periph eral ret in al lesion s, ret in al breaks, an d ret in al detach m en t . Miot ics, topical β-blockers, an d carbon ic an hydrase in h ibitors form th e m ain st ay of th e t reat m en t of pigm en t ar y glaucom a. Pat ien t s u su ally respon d w ell to argon laser t rabecu loplast y (ALT). Filtering su rger y w ith an t im etabolite is don e in advan ced an d refractor y cases.

8 Glaucoma 249

Fig . 8.3 Proper placement of laser application in laser trabeculoplast y. This magnified cross section of the angle area shows a properly placed laser beam (L) being applied to the center of the posterior trabecular m eshwork (P) or pigmented band. Notice the laser burns (B) centered on this pigmented band (P). If one were to divide the space bet ween the scleral spur (S) and the Schwalbe line (A) in half (X), the laser burns (B) fall on the center of the posterior half [area bet ween (X) and (S)]. The anterior half of the m eshwork [area bet ween (X) and (A)] is left untreated. Posterior to the scleral spur (S) is the

uveal meshwork (U). Schlemm canal (C). (Courtesy of Highlights of Ophthalmology, “Innovations in the Glaucomas: Etiology, Diagnosis and Management,” English Edition, 2002. Eds: Benjamin F. Boyd, MD, FACS; Maurice H. Lunt z, MD, FACS; Co-Editor: Samuel Boyd, MD.)

Pseudoexfoliation Syndrome

Pseu doexfoliat ion syn drom e (PEX) is an age-related gen eralized disorder of ex- t racellu lar m at rix ch aracterized by produ ct ion an d progressive accu m ulat ion of fibrillar m aterial in th e t issues th rough out th e an terior segm en t . PEX is th e single m ost com m on iden t ifiable cause of OAG, an d it is also a risk factor for cataract su rger y. In ciden ce in creases w ith age an d is m ore com m on in fem ales.

Presentation

Deposit ion of th e grayish w h ite m aterial on th e surface of th e an terior len s capsu le is a com m on , con sisten t , an d diagn ost ic fin ding. Th e deposit ion h ad a classic pattern of th ree zon es (i.e., a relat ively h om ogen eou s cen t ral disk, a gran u lar layered periph eral zon e, an d a clear area separat ing th e preceding t w o).

Th e PEX m aterial is fou n d deposited on th e pupillar y border, corn eal en doth e- lium , iris fu rrow s, an d som et im es even at th e ext raocular m uscles. Oth er associ-

250 Color Atlas of Ophthalm ology

Fig. 8.4 Pseudoexfoliative material seen in a sublux-

ated lens. (Courtesy of Lincoln Freitas)

ated feat u res can be peripapillar y t ran sillum in at ion defect , in sufficien t m ydriasis, posterior syn ech iae, Sam p aolesi lin e, less den se bu t patchy pigm en t at ion of th e t rabecu lar m esh w ork, ph acodon esis, an d iridodon esis (Fig. 8.4).

Differential Diagnosis

Tru e exfoliat ion , pigm en t ar y glau com a, oth er cau ses for m elan in dispersion , pri- m ar y am yloidosis, sen ile iridosch isis, POAG.

Management

PEX pat ien ts require frequ en t m on itoring of IOP, opt ic disk, an d visu al fields. Th e m edical lin e of m an agem en t form s th e in it ial lin e of t reat m en t . ALT is a h igh ly su ccessive t reat m en t for th ese pat ien t s. Filtering su rger y is recom m en ded for th e advan ced cases. Caut ion sh ou ld be t aken w h ile operat ing on pat ien ts w ith PEX for cataract su rger y, as PEX is associated w ith an in creased in ciden ce of len s su blu x- at ion an d vit reou s loss.

Lens-Induced Glaucoma

Lens-induced glaucom as are either OAGs or angle-closure glaucom a. OAGs include lens protein glaucom a, lens particle glaucom a, and phacoanaphylactic glaucom a. Closedangle glaucom as include intum escent lens and lens sublu xation or dislocation.

Lens Pa rticle Gla ucoma

Th e pat ien t h as u n ilateral pain , defect ive vision , lacrim at ion , an d p h otoph obia. In - creased IOP, cells an d flare, w h ite fluffy pieces of len s cor tex in th e an terior ch am - ber, an d open angles are seen . A disru pt ion in th e len s capsule by t raum a or su rger y liberates len s m aterial th at obst ruct s th e t rabecular m esh w ork. In flam m at ion also con t ributes to th e glaucom a. Man agem en t con sists of reduct ion of in flam m at ion an d IOP follow ed by rem oval of th e residu al len s m at ter if n ecessar y.