Fig. 3.15 Necrotizing scleritis in same patient shown in Fig. 3.14; 1 year later, scleral loss has increased, leaving the underlying uvea covered by a thin layer of conjunctiva

Fig. 3.17 Diffuse illumination from a slit-lamp can show the altered pattern of congested vessels in scleritis; new vessel formation around the avascular areas may appear in necrotizing scleritis

Fig. 3.16 Senile scleral plaques. Note the brownish appearance anterior to the insertion of the lateral rectus muscle, due to scleral translucency secondary to calcium deposition

necrosis progresses, the scleral area can become avascular, producing a white sequestrum in the center surrounded by a well-deÞned dark brown or black circle (Fig. 3.13). The slough may be gradually removed by granulation tissue, leaving the underlying uvea exposed or covered by a thin layer of conjunctiva (Fig. 3.14). The same necrotic process without surrounding inßammation is typical of scleromalacia perforans (Fig. 3.15). The sclera in the elderly becomes thinner and more translucent because of a decrease in water and proteoglycan contents. This is accompanied by subconjunctival deposition of lipids, giving the sclera a yellowish color [2]. Calcium phosphate may be deposited in small rectangular areas just anterior to

the insertions of medial and lateral recti muscles in individuals over 70 years of age. These areas, called senile scleral plaques, may become translucent, showing a bluish or brownish color due to the underlying uvea (Fig. 3.16). This increase in translucency is clearly distinguished from that seen in scleral disease, after or without inßammation, because in scleritis the areas do not usually localize only on the insertions of the horizontal recti muscles.

Color photography of the upper face, including both eyes, may show subtle color or shadow changes. This is an important way of documenting the condition for further evaluation of disease progression.

Slit-Lamp Examination

The slit-lamp examination serves mainly to reveal the depth of inßammation, determining which network of vessels is predominantly affected. Because episcleritis never involves sclera, the main object of slit-lamp illumination is to determine whether or not there is scleral edema.

Diffuse Illumination

Diffuse illumination by the slit lamp conÞrms the macroscopic impression of avascular areas with sequestra and/or uveal show (Figs. 3.2 and 3.12Ð 3.15). It also helps to differentiate the conÞguration of the vessels; in episcleritis, congested vessels follow the usual radial pattern, whereas in

Fig. 3.18 Slit-lamp photomicrograph, patient with episcleritis. Note that there is no displacement of the slit beam from underlying scleral edema

Fig. 3.20 Slit-lamp illumination may help to evaluate the depth of corneal involvement; this patient had peripheral ulcerative keratitis and necrotizing scleritis associated with rheumatoid arthritis

Fig. 3.19 Slit-lamp photomicrograph, patient with scleritis. Note the displacement, anteriorly, of the slit beam as it sweeps across an area of scleral edema underlying the dilated vessels of the conjunctiva and the superÞcial and deep episcleral vascular plexuses

scleritis this pattern is altered and new abnormal vessels are formed. This neovascularization usually takes place around the avascular areas (Fig. 3.17).

Slit-Lamp Illumination

Slit-lamp white illumination detects the depth of maximum vascular congestion and scleral edema. Because in episcleritis the vascular congestion is in the superÞcial episcleral network, the anterior edge of the slit lamp is displaced forward because of underlying episcleral edema; the posterior edge of the slit-lamp beam is ßat (Figs. 3.10 and 3.18). In scleritis, the maximum vascular congestion is in the deep episcleral network; the posterior edge of the slit-lamp beam is

displaced forward because of underlying scleral edema (Figs. 3.11 and 3.19). There is also some congestion in the superÞcial episcleral network; the anterior edge of the slit-lamp beam is displaced forward because of underlying episcleral and scleral edema. The topical application of a vasoconstrictor, such as 10% phenylephrine, makes detection of the congested episcleral network easier; because the vasoconstrictor blanches the superÞcial network without signiÞcant effect on the deep network, the eye appears white in episcleritis but remains congested in scleritis.

Slit-lamp illumination is also important in evaluating the depth and nature of associated corneal pathology (Fig. 3.20), the presence and degree of cells in the anterior chamber or vitreous, and the existence of synechiae.

Red-Free Illumination

Red-free illumination with a green Þlter in the slit lamp helps determine with certainty the areas of maximum vascular congestion, areas with new vascular channels, and areas that are totally avascular.

Red-free illumination is also useful to further study the areas of white blood cell inÞltration of the episcleral tissue, manifested as yellow spots; because these areas are found in episcleritis, their detection makes the differentiating between episcleritis and scleritis easier.