老年性白內障手術後高階像差變化及視覺品質之研究

Impact of Cataract Surgery on High-Order Aberration And Functional Vision

蘇姵元(Pei-Yuang Su)

指導教授 ： 胡芳蓉

國立臺灣大學/醫學院/臨床醫學研究所/碩士(2007年)

https://doi.org/10.6342/NTU.2007.03365

摘要

隨著近年來白內障手術儀器的發明、人工水晶體材質和設計、植入系統的改進及手術技巧的成熟 ，對於白內障病患的治療目標不僅止於視力的恢復，更期望達到趨近完美的視覺品質。 要達到提升視覺品質的目的，除了用光學鏡片矯正低階像差（包括：近視、遠視、散光…等）外，還必須盡可能去除眼球光學路徑中所產生的高階像差，才能使影像能精準的在視網膜上呈現。

眼球光學路徑中的高階像差主要是由角膜及水晶體兩個部份產生，隨著老化過程角膜及水晶體的高階像差都會逐漸增加，因而影響視覺品質。然而白內障手術去除了混濁的水晶體，但是所植入的傳統球面水晶體（spherical intraocular lens）雖然提供了透明無瑕的光學區，卻忽略了角膜所產生的高階像差，尤其是球面像差（spherical aberration）。因此有研究設計出新型態非球面人工水晶體（aspherical intraocular lens），希望藉由進一步矯正角膜球面像差來增進白內障受術後病患之視覺品質。

本研究利用電腦角膜地形儀、前導波像差分析儀及電腦分析軟體；另外測量對比視力及對比敏感度作為視覺品質指標，以研究分析：一、年齡對病人角膜表面及眼球整體高階像差的影響。二、接受白內障超音波乳化術併人工水晶體植入的病人手術前後角膜及眼球整體高階像差的變化。三、比較接受白內障超音波乳化術併植入傳統球面人工水晶體(spherical IOL)，或新型態非球面人工水晶體(aspherical IOL)術後高階像差及視覺品質的不同；並分析其可能影響因子。

研究結果發現：隨年齡增加，各階角膜像差無變化，眼球整體高階像差漸增，是由於水晶體隨年齡變化造成球面像差漸增所致。白內障手術前後角膜高階像差無變化；手術後眼球整體球面高階像差增加，主要是由於植入傳統球面人工水晶體造成。白內障手術後植入新型態非球面人工水晶體明顯降低了眼球整體球面像差，但與植入傳統球面人工水晶體比較，在瞳孔不大於4.5公厘的情況下，不論對比視力或對比敏感度兩組無差別，因此並無提供較佳之視覺品質。

未來可以根據這些研究結果作為改進人工水晶體設計、並且對於不同人工水晶體植入前病患條件之選擇提供一參考方向，甚至期待有個別化（customized）人工水晶體設計的出現，使白內障病患手術後能達到更近完美的視覺品質。

關鍵字

白內障手術 ； 視覺品質 ； 高階像差

並列摘要

With the advances in surgical instruments, IOL design and material, IOL delivery system and surgical technique, the small cornea incision cataract surgery with implantation of IOL have become a successful procedure that provides fast visual rehabilitation and minimum surgical complications. However, improvement of postoperative visual acuity is not the only concern today but also the visual quality and functional vision. Therefore, eliminating optical aberrations,especially high-order aberrations（HOAs）is one way to achieve the goal.
The optical aberrations are mainly from two parts of the eye, cornea and lens. Both corneal and lenticular HOAs increase during the aging process, therefore affect the functional vision. Though the opacified lens is replaced by a crystal clear optics during the cataract surgery, the disturbance of the compensatory effect of nature lens to positive corneal spherical aberration has been made by the conventional spherical intraocular lens. Therefore a new IOL design with aspherical anterior surface was developed during recent years, which generate negative spherical aberrations to compensate for corneal aberration, in order to improve functional visions for cataract patients.
In this study, we use corneal topography and wavefront aberrometer to analyze corneal and total ocular high-order aberrations. In addition, we use contrast sensitivity and contrast acuity as indicators of visual function and try to investigate: 1) the impact of aging on corneal and total ocular HOAs 2) the change of HOAs after the cataract surgery 3) to compare intraindividually the HOAs and functional vision between implantation of spherical and aspherical IOLs.
The results reveal that: Corneal HOAs, including total 3rd, total 4th, total 5th order, coma and primary spherical aberrations, have minimal changes with increase of age. After the small incision clear cornea cataract surgery with , the corneal HOAs increase minimally, but the total ocular HOAs increase significantly compare to normal phakic eyes, especially the total 4th –order and primary spherical aberrations. Compare to conventional spherical IOLs, implantation of aspherical IOLs indeed reduce the ocular spherical aberrations. As for the functional vision, we don’t see significant improvement of aspherical IOLs over conventional spherical IOLs. We speculated that patients with smaller pupil size may not gain the visual benefit provided by the aspherical IOLs.
Aberrations affect vision differently, further investigation for customized IOLs, with ranges of aberrations corrected to suit individual needs, may be needed.

並列關鍵字

cataract surgery ； functional vision ； high-order aberrations

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