A 22-year-old male presents with 4 episodes (2 on the right, 2 on the left) of visual loss associated with pain on eye movements. Now he mainly has problems with the Uhthoff phenomenon and visual fading. The unaided high-contrast visual acuity (VA) 6/6 (US notation 20/20) on the right (RE, OD), 6/24 (20/80) on the left (LE, OS); color vision RE Ishihara 17/17, LE 1/17; and superior nasal VF defect on the left to confrontation.

The confocal scanning laser ophthalmoscopy (cSLO) and OCT scans are shown in Fig. 5.1. The green circle in the cLSO image represents the peripapillary ring scan taken. The corresponding OCT B-scan is shown to the right. Note that the scale of the x- and y-axes is proportional in the cSLO scan, but stretched for the y-axis for the OCT scan (200 μm marker in bottom-left corner).

The innermost retinal layer imaged on the OCT B-scan is the retinal nerve fiber layer (RNFL). This layer is of strong reflectivity and can almost always be well distinguished from the other layers. Next, there are the ganglion cell layer (GCL), inner plexiform layer (IPL), and inner nuclear layer (INL). Typically, the image contrast between the GCL and IPL is poor. The INL can be well recognized as a darker gray band in the middle of the retina. Then there are the outer plexiform layer (OPL) of lighter gray and the outer nuclear layer (ONL), which takes a darker gray shade (see also Figure 2.1 for consensus nomenclature in the chapter by Evangelou and Alrawashdeh). The four outer hyper-reflective bands are best seen in macular scans and typically referred to as the external limiting membrane (ELM), the boundary between the inner and outer photoreceptor segments, the Verhoeff membrane, and the retinal pigment epithelium (RPE) [3].

In this case there is bilateral RNFL loss. These data are represented in the summary graph to the bottom left of the figure. The global average is the most frequently reported value, in the right eye for this case 81 μm (yellow circle in the middle in Fig. 5.1 [4]). The corresponding normal value is 99 μm (given in green letters). Next there is a breakdown of data for individual sectors, nasal superior (NS), nasal (N), nasal inferior (NI), temporal inferior (TI), temporal (T), and temporal superior (TS). Finally a small fraction of the temporal sector is singled out as the papillomacular bundle (PMB). This area is most frequently affected in MSON. Here a value of 43 μm is less than the reported normal value of 59 μm (green letters). The nasal to temporal ratio (N/T) is also reported.

In clinical routine, the thickness diagram to the right is also useful. The color-shaded areas are based on thickness data from a normal population. The bold green line represents the median and the green-shaded area the reference range. Borderline data are shown as blue or yellow, RNFL thickening as purple, and RNFL thinning as red.

In this case there is peripapillary RNFL loss for the PMB on the right and both temporally and nasally on the left.

In this case magnetic resonance imaging (MRI) confirmed inflammation of the optic nerve but also showed more than four lesions elsewhere in the central nervous system (CNS). These lesions fulfilled the radiological criteria for dissemination in time and space for multiple sclerosis. The patient has a clinical diagnosis of a clinically isolated syndrome (CIS) with a high chance to having a relapse in the future and then being diagnosed as clinically definite MS [4].

A 33-year-old female was referred with blurred vision and dyschromatopsia in her left temporal field, which was associated with left facial pain and headaches (VAS 10/10). The symptoms had fully recovered within 1 week. She now suffers from the Uhthoff phenomenon, the Pulfrich phenomenon, and daytime glare disability. At the time MRI, magnetic resonance angiography (MRA), and computed tomography (CT) imaging performed elsewhere were reported as normal.

The OCT scan taken about 14 days after onset is shown in Fig. 5.2. As in the previous case, the peripapillary ring scan is shown at the top for the right eye (to the left in Fig. 5.2) and left eye (to the right in Fig. 5.2). In the left eye there is a swollen peripapillary RNFL. The cSLO image also shows looping of the blood vessels over the swollen RNFL at the optic disk margin. Compared to the right eye, veins appear to be more distended on the left. This can be seen both in the cSLO image and the OCT scan. There is also some thickening of the outer retinal layers suggestive of fluid shifts or possibly cytotoxic or vasogenic edema. This is interesting because hitherto disk edema was attributed to swollen axons as a consequence of stasis of axonal flow only.

In addition to the previous case, here the macular volume scan is also shown at the bottom of Fig. 5.2. The composite image of the macular volume scan contains three images. The large image consists of a semi transparent retinal thickness map overlaying the cSLO image. The superimposed blue segmented circles are the 1 mm, 3 mm, and 6 mm ETDRS grid (a frequently used measurement grid). Summary thickness data for individual sectors of the ETDRS grid are presented to the right as absolute numbers and as a color-coded thickness map. Numeric data refer to averaged thickness in micrometers (black letters) and averaged volume data in mm³ (red letters). In this case the total averaged ETDRS grid volume data are 9.43 mm³ for the right eye and 9.40 mm³ for the left eye. This shows that macular volume data are not much affected by disk swelling in optic neuritis. For illustration, the segmentation on which the thickness data are based is given at the very bottom of the graph. The two red lines in the OCT B-scan (taken at the location of the green horizontal reference line in the macular cSLO scan) reveal that all thickness map data were based on the total retinal thickness—a very robust and well-validated measure.

In conclusion the OCT showed optic disk swelling on the left. Brain and spinal cord imaging were normal. This patient has a diagnosis of an isolated left optic neuritis (ION) [1, 5].

A 26-year-old female experienced 2 episodes of blurred vision in her left eye over the past 2 years. Both were associated with pain on eye movements and recovered within only a few days. There was VA 6/9 (US notation 20/30) with full color vision. There was a left RAPD.

The reader should now be familiar with the OCT data presented in Fig. 5.3. The OCT scan reveals temporal loss of RNFL on the left. Brain and spinal cord imaging were normal. She has a diagnosis of relapsing isolated optic neuritis (RION) [5, 1].

A 24-year-old female experienced 10 episodes of relapsing optic neuritis over a 4-year period. Each episode was associated with pain on eye movements. Her BCVA is poor OD (right eye) HM and OS (left eye) 6/30 (20/100). She has lost color vision. Repeated MRI brain and spinal cord imaging showed inflamed optic nerves, but no sign of CNS inflammation elsewhere. She does not have anti-AQP4 autoantibodies. Relapses always occur on tapering off steroids. She has a clinical diagnosis of chronic relapsing inflammatory optic neuropathy (CRION) [6]. Upon each relapse she receives hyperacute treatment with steroids [7].

The OCT scan is shown in Fig. 5.4. There is severe binocular RNFL atrophy. The peripapillary RNFL atrophy seen here is much more severe than what is seen at first presentation with typical MSON.

A new measure shown in this figure is the use of longitudinal data. The first scan was taken at baseline (thin black line in thickness diagram) and the second scan at 2-year follow-up (bold black line in thickness diagram). Despite the frequent episodes, the RNFL layer thickness remained essentially unchanged over the 2-year period.

A 25-year-old female presented with NPL in her right eye following 1 severe episode of optic neuritis. There was BCVA OS 6/4.8 (20/16). She tested positive for anti-AQP4 autoantibodies. Under treatment with azathioprine, she experienced another episode of optic neuritis that affected the remaining good, left eye. Hyperacute treatment with steroids was initiated [7]. In total, 4 further episodes occurred and it was possible to preserve a BCVA OS of 6/6 (20/20).

The OCT scan is shown in Fig. 5.5. Severe loss of RNFL can be seen on the right. Despite a number of relapses, the RNFL remained relatively preserved on the left. As in the case before, the thick black line in the thickness diagram represents the baseline data and the bold line the last follow-up 2 years later. She has a diagnosis of neuromyelitis optica optic neuritis (NMO-ON) [8].

A 54-year-old male patient was diagnosed 5 years ago with primary open-angle glaucoma (PAOG). At the time his IOP spiked to 38 mmHg on the right and 34 mmHg on the left. About a year ago, he noticed 1 episode of scintillations in his left eye. He cannot remember if there was any pain on eye movements. His current problem is trying to judge the driving trajectories of other cars in busy traffic. There was BCVA 6/5 (20/16) bilaterally with mild dyschromatopsia on the left eye and a left RAPD.

The OCT scan is shown in Fig. 5.6. The OCT demonstrates a glaucomatous disk on the right, but more severe RNFL loss than expected alone from glaucoma on the left. The bold black line in the thickness diagram refers to the OCT scan shown in Fig. 5.6 and the thin black line in the thickness diagram to the OCT taken 5 months earlier.

These findings are suggestive of an episode of an isolated optic neuritis on the left. As expected from longitudinal OCT data in ON [9], RNFL atrophy has now plateaued.

A 45-year-old female was referred with unexplained visual loss. On the 1st of January, she developed severe headaches, nausea, and vomiting. She was bedbound for 8 days, following which she noticed that her vision had gone blurred. There was a left RAPD, BCVA RE 6/6 (20/20), LE 6/36 (20/120). She did miss 5 Ishihara plates on the left.

The OCT scan is shown in Fig. 5.7. The OCT demonstrated severe bilateral nasal RNFL thinning as seen following chiasmitis. In addition there is more prominent loss of the PMB on the right explaining the poorer VA and color vision. She had a diagnosis of chiasmitis, which is clinically associated with severe headaches, nausea, vomiting, and binocular loss of vision. Chiasmitis is usually not associated with MS but can be occasionally. It is associated with NMO [1, 2, 10, 11].

A 27-year-old male patient with a lifelong history of a pendular seesaw nystagmus noticed a shadow obscuring a very small part of his central visual field on the left. There were BCVA OD 6/12 (20/40), LE 6/24 (20/80), N4.5 bilaterally, and normal color vision. The nystagmus made funduscopy challenging. It was, therefore, not possible to be sufficiently certain that macular pathology was excluded.

The OCT line scan revealed a small pre-foveal floater on the left (arrow in Fig. 5.8). This small floater also casts a shadow, which is just visible to the right of the foveola, explaining his new symptoms. Note that because of the nystagmus, this OCT scan was only possible with 1 single horizontal line (dashed green horizontal reference line in cSLO image).

Electrodiagnostic testing was consistent with achiasma and the well-defined foveola, seen in the OCT, explains his relatively good vision. He has a diagnosis of achiasma [12].

A 42-year-old female presents with a 2-year history of binocular visual snow and an area of blurred vision clearly depicted on the Amsler chart. She has an overlap diagnosis between entoptic phenomena due to her PVD and visual snow [13].

The OCT scan is shown in Fig. 5.9. The OCT shows minimal central PVD in the left eye in the area corresponding to the central VF defect on the Amsler chart. In the right eye, it can be seen that the vitreous has already retracted completely from the entire macular area.

Nonorganic visual loss occured in a 23-year-old male. Visual acuity (VA) had decreased on the right from 6/6 (20/20) to count finger (CF), 9 months previously. Five months earlier VA decreased on the left from 6/6 to CF. He still can read Ishihara charts and walk freely between chairs in a dimmed examination room. The visual problems coincide with him being made redundant at work.