黄斑部錐体機能から推察する網膜色素変性の左右差

Difference in cone function between right and left eyes in retinitis pigmentosa

要約　目的：網膜色素変性での錐体機能の左右差の検討。対象と方法：過去11か月間に網膜色素変性と診断した初診患者71例を対象とした。男性31例，女性40例で，すべて両眼発症であり，年齢は平均45±16歳であった。黄斑部局所網膜電図と光干渉断層計（OCT）を用い，視力はlogMARで評価した。症例はOCTで描出される視細胞の内節と外節の境界線の所見から，2mm以下の1型と2mmを超える2型に分類した。結果：病初期と推定される1型は24人48眼，進行期と推定される2型は21人42眼で，年齢はそれぞれ48±18歳，45±17歳であった。視力は両型とも左右眼の間に弱い相関があった。網膜電図の振幅は，1型では弱い相関，2型では強い相関が左右眼の間にあった。網膜電図のb波とOP波は，1型，2型ともに左右眼の間に強い相関があった。潜時は両型ともにa波とb波ともに左右眼の間に弱い相関があり，OP波には強い相関が左右眼の間にあった。結論：網膜色素変性での錐体機能は，病初期から両眼がほぼ同等に障害される。

Abstract.　Purpose：To report difference in cone function between pairs of eyes in retinitis pigmentosa. Cases and Method：This study was made on 71 patients who were diagnosed with retinitis pigmentosa during a 11-month period. The series comprised 31 males and 40 females. The age averaged 45±16 years. All were bilaterally affected. Cases were evaluated by optical coherence tomography（OCT）and focal macular electroretinogram（fmERG）. The visual acuity was expressed as logMAR. Cases were divided into 2 types. Eyes were assigned to type 1 when the junction between inner and outer segment of photoreceptor was less than 2mm and to type 2 when it was 2mm or more. Results：Type 1, which would belong to earlier stage of retinitis pigmentosa, included 48 eyes of 24 patients. The age averaged 48±18 years. Type 2 included 42 eyes of 21 patients. The age averaged 45±17 years. Both types showed a weak correlation between both eyes regarding visual acuity. Amplitude of fmERG between both eyes was weakly correlated in type 1 and strongly in type 2. Both types showed strong correlations between both eyes regarding b and OP waves. Both eyes showed weak correlations between both eyes regarding implicit time. Conclusion：Cone function is equally affected in both eyes from the early stage of retinitis pigmentosa.