Korelacija debljine sloja živčanih vlakana te makularnoga područja mrežnice i oštećenje vidnoga polja kod unilateralne ambliopije [The correlation between the thickness of the layer of nerve fibers and the macular area of the retina and changes in the visual field, with unilateral amblyopia]

Perić, Sanja (2017) Korelacija debljine sloja živčanih vlakana te makularnoga područja mrežnice i oštećenje vidnoga polja kod unilateralne ambliopije [The correlation between the thickness of the layer of nerve fibers and the macular area of the retina and changes in the visual field, with unilateral amblyopia]. PhD thesis, Sveučilište u Zagrebu.

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Abstract

In Croatia, it has been estimated that as many as 200 thousand people are amblyopic. It is the most common cause of decreased unilateral visual acuity among children and younger adults with the expected incidence of 1.6 – 3.6% although the incidence can be higher within the population with inadequate health care. It is believed that amblyopia is primarily a cortical phenomenon, caused by the unequal competitive input signal which arises from each eye and travels to the primary visual cortex. Up until now, opinions on structural retinal change are divided. The aim of this study is to investigate the presence of structural and functional changes in the macula and the nerve fiber layer of the amblyopic eye. If such changes are present, is there a certain correlation between structural and functional changes. 60 subjects with unilateral amblyopia were included in the study. The subjects were divided into two groups based on the severity of amblyopia; the subjects with severe amblyopia (visual acuity 0.1 – 0.4) and the subjects with a mild form of amblyopia (visual acuity 0.5 – 0.8). All the subjects underwent OCT imaging of the macular field and the optic nerve head, as well as automated perimetry of the amblyopic and the unaffected eye. The main result of the study is that the structural changes of the macula in the amblyopic eye are present in the form of thickening. Thickening of the macula was found in all 9 observed areas. Severe amblyopia has significantly affected the increased macular thickening in the area of foveola, the central area within 1 mm, and the inner part of macular ring (within 3 mm). The changes in thickness of the nerve fiber layer have not been recorded neither in amblyopic nor in the unaffected eye. By examining the correlation between the parameters obtained by the OCT and the visual field, it was established that the measured mean values of the macula and the RNFL thickness of normal and amblyopic eye do not have the expected positive correlation with MD and sLV, nor do they have a negative correlation with the value of MS. According to our results, we assume that the changes in visual field of amblyopic and healthy eyes are more affected by the strength of the input signal and the changes in the visual cortex and the lateral geniculate body rather than by the thickness of the macular area.

Abstract in Croatian

Procjenjuje se da je u Hrvatskoj čak 200 tisuća ljudi slabovidno. To je najčešći uzrok jednostrane slabije vidne oštrine kod djece i adolescenata, s očekivanom incidencijom od 1,6 do 3,6%, iako incidencija može biti veća kod populacije s lošijom medicinskom skrbi. Smatra se da je slabovidnost primarno kortikalni fenomen, uzrokovan nejednakim kompetitivnim ulaznim signalom koji dolazi od dva oka u primarni vidni korteks (V1). Za sada su mišljenja o strukturnoj promjeni mrežnice podijeljena. Cilj je ovoga istraživanja bio ispitati postoje li strukturne i funkcionalne promjene u makuli i sloju živčanih vlakana u ambliopnom oku. Ako postoje, postoji li povezanost između strukturnih i funkcionalnih promjena. Ispitivanje je uključivalo 60 ispitanika s unilateralnom ambliopijom. Ispitanici su prema težini ambliopije bili podijeljeni u dvije skupine; ispitanici s težom ambliopijom (vidna oštrina 0,1 – 0,4) i ispitanici s blažim stupnjem ambliopije (vidna oštrina 0,5 – 0,8). Svim je ispitanicima napravljeno OCT snimanje makularnoga područja i glave vidnoga živca, kao i kompjuterizirano vidno polje na slabovidnom i dobrom oku. Glavni je rezultat našega istraživanja da postoje strukturne promjene makularnoga područja kod ambliopnog oka u smislu zadebljanja. Zadebljanje makule našlo se u svih 9 promatranih područja. Ambliopija težeg stupnja utjecala je značajnije na povećanu debljinu makule u području foveole centralnoga područja unutar 1 mm, i u unutarnjemu dijelu makularnoga prstena (unutar 3 mm). Nisu zabilježene promjene u debljini sloja živčanih vlakana u ambliopnom, ni na zdravom oku. Ispitivanjem korelacije između parametara dobivenih OCT-om i vidnoga polja ustanovilo se da izmjerene srednje vrijednosti debljine makularnoga područja i RNFL-a dobrog i slabovidnog oka nemaju očekivanu pozitivnu korelaciju s MD i sLV vrijednostima, kao ni negativnu korelaciju s vrijednošću MS-a. Prema našim rezultatima, pretpostavljamo da na promjene u vidnome polju ambliopnog i dobrog oka više utječe snaga ulaznoga signala i promjene u vidnome korteksu i lateralnome koljenastome tijelu, nego debljina makularnoga područja.

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