原発閉塞隅角疑いとZinn小帯脆弱—Zinn小帯脆弱度分類を用いた検討

Primary angle closure suspected and zonular weakness: a study using the categorization of weak zonule

要約　目的：原発閉塞隅角疑い（PACS）におけるZinn小帯脆弱度の分布を検討したので報告する。

対象と方法：対象は2024年10月〜2025年3月に小沢眼科内科病院で施行した白内障手術症例のうち，PACS群51例（75.2±8.7歳，男性12例），および対照群93例（75.7±7.9歳，男性31例）である。囊内固定の成功率，囊安定化デバイスの使用率を調べ，Zinn小帯の脆弱性評価には前囊切開時の所見に基づくZinn小帯脆弱度分類（Grade N：normal，W：weak，VW：very weak，EW：extremely weak）を用いて手術ビデオを解析し，Zinn小帯脆弱度の分布を2群間で比較した。PACS群のうちZinn小帯脆弱度がGrade Nを正常群，Grade W，VW，EWを脆弱群とし，年齢，眼軸長（AL），前房深度（ACD），水晶体厚（LT），lens vault（LV）を群間で比較した。

結果：Zinn小帯脆弱度は対照群でGrade N：92例，Grade W：1例，Grade VW：0例，Grade EW：0例だった。PACS群でGrade N：44例，Grade W：6例，Grade VW：1例，Grade EW：0例であった。Zinn小帯脆弱度の分布はPACS群でGradeが高い例がより多く認められた（p＝0.031）。囊内固定は全例で成功し，囊安定化デバイスの使用はなかった。PACS群のうちZinn小帯正常群と脆弱群の背景因子すべてに有意差はなかった。

結論：白内障手術中のPACSのZinn小帯脆弱は正常眼に比べて頻度が高いが，眼内レンズの囊内固定に影響するような重度のZinn小帯脆弱は稀であった。

Abstract　Purpose：To investigate the distribution of zonular weakness in eyes with primary angle closure suspected（PACS）.

Subjects and Methods：Among cataract surgeries performed at Kozawa Eye Hospital and Diabetes Center between October 2024 and March 2025, 51 eyes with PACS（mean age 75.2±8.7 years；12 men） and 93 control eyes（mean age 75.7±7.9 years；31 men） were enrolled.

　The success rate of in-the-bag intraocular lens（IOL） fixation and the use of capsular stabilization devices were evaluated. Zonular integrity was assessed by reviewing surgical videos using the zonular weakness classification proposed by Yaguchi et al., based on findings at capsulorhexis：Grade N（normal）, W（weak）, VW（very weak）, and EW（extremely weak）. The distribution of zonular weakness grades was compared between the two groups.

　Within the PACS group, eyes were further divided into a normal zonule group（Grade N） and a zonular weakness group（Grades W, VW, and EW）, and demographic and biometric parameters-including age, axial length（AL）, anterior chamber depth（ACD）, lens thickness, and lens vault（LV）-were compared between the two subgroups.

Results：In the control group, zonular weakness was graded as Grade N in 92 eyes, Grade W in 1 eye, and Grade VW or EW in none. In the PACS group, 44 eyes were classified as Grade N, 6 as Grade W, 1 as Grade VW, and none as Grade EW. The distribution of zonular weakness grades showed a significantly higher proportion of eyes with increased severity in the PACS group compared with the control group（p＝0.031）. In-the-bag IOL fixation was successfully achieved in all eyes, and no capsular stabilization devices were required. Within the PACS group, no significant differences were observed in any demographic or biometric parameters between the normal zonule and zonular weakness subgroups.

Conclusion：Zonular weakness during cataract surgery was more frequently observed in eyes with PACS than in normal eyes；however, severe zonular weakness that would compromise in-the-bag IOL fixation was rare.