Ординатура / Офтальмология / Учебные материалы / Uveitis Text and Imaging Text and Imaging Text and Imaging 2009

Figure 15: Retinal Thickness/Volume displays both thickness and volume for each eye showing both eyes scan groups with Radial Lines or Macular Thickness Map protocols

Retinal Thickness/Volume (Figure 15)

This displays both thickness and volume for each eye showing both eyes scan groups with Radial Lines or Macular Thickness Map protocols. The upper maps show colour-coded retinal thickness and lower maps show either average retinal thickness in microns or the volume in mm3. On the lower right, average foveal thickness in microns +/- standard deviation for the centre point and the total macular volume in mm3 are displayed.

Retinal Thickness Volume Tabular (Figure 16)

This protocol, in addition to Retinal Thickness/Volume analysis, also gives a data table that displays thickness and volume quadrant average, ratios and differences among various quadrants and between the eyes.

When applied to ‘Fast Macular Thickness Scan’ it also shows the normative data colour code in each A- scan location.

Retinal Thickness/Volume Change (Figure 17)

This protocol gives the change in retinal thickness or volume between examinations.

INDICATIONS IN UVEITIS

OCT has been found to be useful in the imaging of intraocular inflammations by providing the following information:

Figure 16: Retinal Thickness Volume Tabular protocol’also gives a data table that displays thickness and volume quadrant average, ratios and differences among various quadrants and between the eyes

Figure 17: Retinal Thickness/Volume Change protocol gives the change in retinal thickness or volume between examinations

RETINITIS VERSUS CHOROIDITIS

Posterior uveitis is classified according to the anatomic location of the lesions. OCT is able to define the extent, depth and thickness of the inflammatory lesion. It helps to localize the level of retina-choroid harbouring the lesion. This localisation is helpful in not only diagnosing the disease but also in monitoring the response to treatment. In patients with active toxoplasmosis, it shows a hyper-reflective lesion in the inner retina that conforms to the location of retinitis (Figure 18).

Figure 18: OCT Line scan of toxoplasmic retinochoroiditis showing a hyper-reflective lesion in the inner retina that conforms to the location of retinitis

Figure 19: OCT Line scan of congenital toxoplasmosis scar showing hyper-reflective shadows in the outer retina-choroid

The congenital toxoplasmosis scars, on the other hand, are seen as hyper-reflective shadows in the outer retina-choroid (Figure 19).

CYSTOID MACULAR OEDEMA (CME)

CME is commonly associated with intraocular inflammation due to various aetiologies. OCT is useful in depicting the cystic spaces that are seen as hyporeflective spaces with intervening hyper-reflective septae. The retinal thickness can be measured in microns in the central 3.5 mm or 6 mm. When compared to fundus fluorescein angiography (FFA), OCT was found to be effective in diagnosing CME. OCT had 89% sensitivity for diagnosing CME compared to FFA.12 Markomichelakis et al13 described three

patterns of uveitic macular oedema: (1) Diffuse macular oedema that was seen as sponge-like thickening of the retina with low-reflectivity was seen in 54.8% the eyes; (2) CME with clearly defined intra-retinal cystic spaces was seen in 25%; and (3) Serous retinal detachment with fluid accumulation between RPE and neurosensory retina was seen in 5.9% of cases. In addition, 14.3% of the eyes had diffuse macular oedema and retinal detachment. OCT also identified 8 eyes (9.5%) with vitreomacular traction. There was no significant correlation between the types of macular oedema and uveitis entity. OCT was found to be very effective in diagnosing macular oedema in eyes with moderate amount of vitritis and asteroid hylosis.14,15 This quantification is useful in monitoring response to an intervention like depot or systemic corticosteroids, immunosuppressants, etc. There has been lot of interest lately in the administration of intravitreal triamcinolone acetonide ; OCT aides in accessing the response to intervention in these eyes by precise measurement of central retinal thickness (Figures 20 and 21).16

SEROUS RETINAL DETACHMENTS

OCT is very useful in studying serous retinal detachments in patients of sympathetic ophthalmia and Vogt-Koyanagi-Harada (VKH) syndrome (Figures 22 to 25). Maruyama and Kishi reported two patterns of serous detachments in VKH syndrome: (1) true

Figure 20: A 24-year-old male was seen with Intermediate uveitis and CME. OCT retinal thickness map shows average central retinal thickness measuring 468 + 235 microns. Patient received posterior subtenon injection of triamcinolone acetonide 20 mg

Figure 21: Same eye 4 weeks later showing resolution of CME. OCT retinal thickness map shows average central retinal thickness measuring 210 + 8 microns

Figure 23: OCT Line scan shows accumulation of fluid in the subretinal space

Figure 25: OCT Line scan of the same eye as in Figure 24 shows accumulation of fluid in the subretinal space

retinal detachment seen in 69% of eyes and (2) intraretinal fluid accumulation in the outer retina in 40%. Four eyes had both.17 OCT is also helpful in monitoring response to corticosteroids in these eyes.

CHOROIDAL NEOVASCULAR MEMBRANE (CNVM)

CNVM can develop in any pathologic process that affects RPE-Bruch’s membrane. Multifocal choroiditis, POHS, serpiginous choroiditis, Birdshot chorioretinopathy, toxoplasmic retinochoroiditis and several other inflammatory conditions can develop secondary CNVM.14 When choroiditis heals, it leaves behind a focal area of atrophy. Decompensation of choroidal vessels at this stage might result in the development of CNVM. OCT is helpful in documenting CNVM in a chorioretinal scar (Figures 26 and 27).

Figure 27: OCT Line scan shows hyper-reflective fibrovascular complex with intraretinal cystic changes and fluid accumulation

OCT has been used to study the type of CNVM and finding its correlation to RPE. Zolf et al studied six consecutive patients of subfoveal CNVM and multifocal choroiditis. All these eyes showed CNVM

anterior to RPE and a clear separation zone between RPE and CNVM. All six eyes had successful surgical outcome.18 The authors concluded that the eyes that preoperatively show a hyper-reflective tissue anterior to the RPE, a separation zone and an underlying optically clear zone are the ones that are most amenable to surgery.

VITREORETINAL INTERFACE

OCT is very useful in documenting pathologies at the vitreo-retinal interface, e.g. the formation of an epiretinal membrane (Figure 24). OCT is also helpful in documenting early infiltrates at the posterior vitreous interface (Figures 28 and 29).

DRAWBACKS

OCT requires clear media for light to travel. It is not possible to get a good quality scan in the presence of

Figure 29: OCT Line scan shows hyper-reflective fibrovascular complex. In addition, an epiretinal membrane is seen on the vitroretinal interface

opaque media due to associated anterior uveitis, cataract, corneal oedema, and vitritis.

CASE REPORTS

CASE #1. ACQUIRED OCULAR TOXOPLASMOSIS

A 13-year-old young girl presented with decreased vision in her left eye of two weeks duration. Her visual acuity was 20/400. Fundus examination of left eye showed focal retinitis with overlying focal vitritis (Figure 30 A). OCT line scan through active lesion showed hyper-reflective inner layers with back shadow. Vitreous cells were seen as hyper-reflective dots anteriorly (Figure 30B).

Figure 30A: Fundus examination L/E showed focal retinitis with overlying focal vitritis

Figure 30B: OCT Line scan through active lesion showed hyper-reflective inner layers with back shadow. Vitreous cells were seen as hyper-reflective dots anteriorly

Figure 30C: Repeat fundus photograph showing healed lesion

Figure 30D: Repeat OCT scan through the lesion showing reduced hyper-reflectivity with reduced backshadowing

A diagnosis of toxoplasmoic retinochoroiditis was made. The patient received oral clindamycin and corticosteroids. Three weeks later, visual acuity improved to 20/40 and repeat scan through the lesion showed reduced hyper-reflectivity with reduced backshadowing (Figures 30C and D).

OCT scan through various levels of the CNVM (Figures 32 and 33) showed an area of moderately intense hyper-reflectivity in the outer retinal layers both nasal and temporal to the fovea (arrows) with hyporeflective area under the fovea suggestive of subretinal fluid.

CASE 2: TYPE II CNVM IN TOXOPLASMOSIS

A 25-year-old woman was seen with decreased vision in her right eye of 8 months duration. Her bestcorrected visual acuity was 20/200 in the right eye. She was diagnosed as toxoplasmosis elsewhere and was receiving treatment for the same. Fundoscopy and fluorescein angiography revealed the presence of CNVM adjacent to the scar (Figures 31A-C).

CASE 3: VOGT-KOYANAGI-HARADA’S DISEASE

A 26-year-old boy was seen with decreased vision in both his eyes of 12 days duration. His best-corrected visual acuity was 20/200 in the right eye. Right eye fundus (Figure 34) showed whitish spots in the posterior pole.

The fluorescein angiography showed multiple hypofluorescent spots that showed hyperfluorescence

Figures 31B and C: Fluorescein angiography early and late phase showing the presence of CNVM

Figure 34: Fundus photograph R/E showing whitish spots in the posterior pole

Figure 37: OCT Line scan of the right eye shows an intraretinal pocket of fluid accumulation

in the late phase with two areas of dye pooling suggesting small neurosensory detachments (Figures 35 and 36).

OCT line scan of the right eye (Figure 37) showed an intraretinal pocket of fluid accumulation (arrow). Though the underlying choroid showed moderately increased hyper-reflectivity from the choroid, the increased choroidal thickness could not be appreciated.

The left eye of the patient also showed similar whitish lesions that were hypofluorescent initially and hyperfluorescent in the late phase of fluorescein angiography (Figure 38). The visual acuity was reduced to 20/80.

OCT line scans showed a hyporeflective area nasal to the fovea corresponding to serous retinal detach-

ment. Though retinal pigment epithelium was irregular at some places, no choroidal thickening was appreciable (Figure 39).

After 4 weeks of oral corticosteroid therapy, there was significant clinical improvement with visual acuity improving to 20/30 in the right and 20/20 in the left eye. The repeat fluorescein angiography was unremarkable in both eyes. Repeat OCT line scan of both eyes was normal (Figures 40 and 41). No residual changes were seen.

CASE 4: SYMPATHETIC OPHTHALMIA

A 24-year-old young man suffered trauma in right eye during a roadside accident resulting in closed globe injury with hyphaema, vitreous and choroidal haemorrhage (Figure 42).

Ten days later, while awaiting pars plana vitrectomy in right eye, patient complained of diminished vision in left eye. His best-corrected visual acuity was 20/200 in left eye. Fundus of left eye showed serous retinal detachment that was confirmed on fluorescein angiography (Figures 43A-D).

ICG of left eye showed hyper-permeability from choroid with staining in the late phase. Ultrasound B scan showed diffuse choroidal thickening in the posterior pole. OCT line scan (Figure 44) showed multiple pockets of serous retinal detachments with increased foveal thickness.

Patient responded to intravenous methylprednisolone with reduction in retinal thickness over next 48 hours (Figure 45).

Figure 39: OCT line scan showing a hyporeflective area nasal to the fovea corresponding to serous retinal detachment

Figures 40: Repeat normal OCT line scans of right and left eyes respectively