*2.6.2 Anterior examination*

Intraocular pressures should be measured using Schiotz tonometer, tonopen, Perkins tonometer, or pneumotonometer. Elevated intraocular pressure in patients with retinoblastoma can be secondary to iris neovascularization or angle closure, and has been associated with increased risk of optic nerve invasion and metastatic disease [18].

After intraocular pressure is checked, corneal diameter should be measured with a caliper both in horizontal and vertical directions. Conditions such as persistent fetal vasculature (PFV) is associated with asymmetric corneal diameter size as well as eyes with congenitally elevated intraocular pressures can be associated with buphthalmos and increased corneal diameter.

A portable slit lamp should be used to assess the anterior segment. The clinician should evaluate anterior depth, clarity of the lens, neovascularization of the iris or atrophy, retrolental membrane, anterior chamber cells, nodules of the iris, or anterior vitreous seeds seen behind the lens. Presence of a pseudohypopyon should raise suspicion for endophytic tumor and anterior chamber seeing of cancer. It may be possible to visualize retinal vascular, retrolental masses, or retrolental membranes. Retrolental retinal tissue should reveal blood vessel branching patterns

#### **Figure 2.** *External photograph of young child with leukocoria of the left eye secondary to intraocular retinoblastoma.*

extending towards the periphery of the lens which could be secondary to exophytic tumor, whereas the persistent tunica vasculosa lentis in PFV, vessels should be noted to be growing towards the center of the posterior lens in a disorganized fashion. Retrolental membrane without vascular pattern is suggestive of retinopathy of prematurity rather than RB.

Binocular indirect ophthalmoscopy should then be performed in a step by step fashion. Initially the vitreous should be examined in both eyes for presence of seeding, vitreous hemorrhage, fibrous membranes, or inflammatory debris. If the posterior pole is visible, optic disc and macula should be examined and abnormal findings documented. Examination of the periphery should be performed with scleral depression of the ora serrata in a clockwise or counter-clockwise fashion, with examination of the midperipheral retina and posterior pole for 360 degrees in both eyes.

Small RB lesions can be difficult to detect as there can be poor contrast between the small translucent tumor and the surrounding fundus. Meticulous examination and depression is needed to observe these tumors stereoscopically. Medium sized tumors become more opaque and start appearing white. Large tumors (>4–5 mm) in diameter will begin to have visually obvious blood supply and visually significant feeder vessels should be noted. Many very large lesions (>6 mm) will develop chalky-white calcifications within the body of the tumor. The size and number of all tumors should be noted, with evaluation of subretinal fluid, retinal detachment, and presence of seeding (subretinal or vitreous) (**Figure 3**), and should all be incorporated into a detailed retinal drawing along with fundus photography [12]. Drawing and photography can help the clinician classify the tumor according to existing classification schemes at a later time.
