Neurodegeneration in ocular and central nervous systems: optical coherence tomography study in normal-tension glaucoma and Alzheimer disease*

Abstract

IntroductionGlaucoma is among the leading causes of blindness worldwide. As an optic neuropathy, glaucoma is characterized by progressive retinal ganglion cell death. Elevated intraocular pressure is the only commutable risk factor for glaucoma. However, despite the effective control of intraocular pressure (IOP), the progression of visual field loss suggests that IOP-independent mechanisms may also play a role in glaucomatous degeneration in patients having normal-tension glaucoma (NTG) (1,2).Based on the similarities between glaucoma and neurodegenerative diseases, including the selective loss of neuron populations and common mechanisms of cell injury and death, a contemporary hypothesis has implicated glaucoma as a neurodegenerative disease (3). The IOP-independent mechanisms that cause degeneration in NTG may be similar to the mechanisms at work in neurodegenerative diseases. Some studies have Background/aim: To evaluate, in vivo, the optical coherence tomography (OCT) of the retinal nerve fiber layer (RNFL) and ganglion cell complex (GCC) in patients with normal-tension glaucoma (NTG) and those with Alzheimer disease (AD) in comparison with healthy subjects. Materials and methods:This cross-sectional study included 18 patients with NTG, 20 with AD, and 20 control subjects. An ophthalmologic examination and OCT scans of both eyes were performed in all patients.Results: There was a significant reduction in peripapillary RNFL thickness and macular GCC thickness and a significant increase in the global loss volume (GLV) rate in both the NTG and AD patients when compared to the control subjects (P = 0.004, P = 0.006, P < 0.001, respectively). The statistical evaluation showed no difference in any RNFL or GCC parameters between the AD and NTG groups (P > 0.05). There was a negative correlation between disease duration and average RNFL and GCC thicknesses (r = −0.350, P = 0.027 and r = −0.471, P = 0.002, respectively) and a positive correlation between duration and GLV (r = 0.427, P = 0.006) in the AD group. Conclusion:The average RNFL thickness, GCC thickness, and GLV rates may help in the diagnosis of AD as an additional examination and may provide some important clues about the duration of the disease.

Retinal thickness in Alzheimer's disease: A systematic review and meta‐analysis

“…Possibly, AD is a risk factor for glaucoma, or AD and glaucoma share a pathophysiological process with retinal neurodegeneration as final common pathway. Two recent studies of Eraslan et al and Cesareo et al, measuring RNFL with OCT, visual field defects with frequency doubling technology, and optic nerve head morphology with HRT, showed similar patterns of RNFL thinning, visual field loss, and optic nerve head morphology in AD and normal tension glaucoma [10,44]. Consequently, it seems very challenging to discriminate retinal changes due to AD from retinal changes due to glaucoma.…”

“…With OCT, retinal changes are visualized both in ophthalmological disease and in neurodegenerative disease. Previous studies have shown that the retinal nerve fiber layer (RNFL) thickness and ganglion cell layer (GCL) thickness are reduced in subjects with multiple sclerosis (MS) [5], Parkinson disease (PD) [6], and AD [7–31].…”

Optical Coherence Tomography in Alzheimer’s Disease and Other Neurodegenerative Diseases

“…Current OCT research investigating visual system degeneration in various neurological diseases produces compelling evidence for retinal thinning, particularly in MCI and AD (see summary in Table 1 ). While a subset of these studies have shown specific deterioration of the GCL along with the inner plexiform layer (IPL) ( 33 , 37 , 71 , 74 ), the majority have demonstrated thinning of the RNFL, especially in the superior and inferior quadrants, with a focus on the peripapillary region [peripapillary retinal nerve fiber layer (pRNFL)] surrounding the optic disk ( 21 , 34 , 35 , 37 , 50 , 65 , 68 , 71 , 74 , 78 , 83 , 92 , 113 , 114 ). As the inner-most layer of the ocular fundus, this area is composed of RGC axonal projections leading to the optic nerve.…”

“…Although a couple of studies failed to find differences in retinal thickness between patients with AD or MCI and matched HC ( 45 , 92 ), many more studies detected significant RNFL structure abnormalities in AD and MCI patients compared with matched HC ( 32 , 37 , 38 , 41 – 44 , 46 , 50 , 67 , 71 – 73 , 75 , 76 , 78 , 79 , 81 , 82 , 87 , 114 – 116 ). These reports have indicated that RNFL thickness in the patients was substantially decreased in all quadrants or that there were specific reductions in the supraretina and infra-retina.…”

Retinal and choroidal morphological changes in Huntington's disease

“…Установлено также снижение толщины сетчатки во всех отделах макулярной зоны с максимальным истончением в периферических отделах, относящихся к магноцеллюлярной системе [26]. Подобный паттерн атрофии клеток отмечают при глаукоме [27,28], сходство в патогенезе данных заболеваний подтверждают и другие исследования [29,30]. Результаты оценки толщины СНВС при болезни Паркинсона более разнородны и указывают на преимущественное снижение толщины СНВС в височном секторе [18,20,29], что больше соответствует атрофии зрительного нерва при митохондриальных заболеваниях, таких как наследственная оптическая невропатия Лебера [31].…”