**4. Capsular block syndrome evaluation before and after treatment using SD-OCT**

two groups. Compared to 1-plane manual CCI, we mainly used a 2-plane CCI in femtosecond group. As previous studies have mentioned, a 2-plane CCI with a partial lamellar cut positioned parallel to the collagen lamellae may improve the shearing force effects of the stromal collagen lamellae across the entire depth of the cornea [25–27]. Posterior wound retraction, defined as an abrupt step-off or recession of the central edge of the posterior wound surface, was not observed in manual group in this study. This may be attributed to the relatively high incidence of posterior wound gape, in which the posterior wound margins were still separated. A high incidence of posterior wound retraction in the femtosecond group may indicate remodeling of the CCI resulting from endothelial cell necrosis, molecular dissociation, and biomechanical and thermal changes from the femtosecond laser [28]. A previous study, using transmission electron microscopy confirmed the difference between femtosecond laser corneal flap formation (necrotic keratocytes) and microkeratome corneal flap formation (keratocyte apoptosis), which may potentially explain the different incidence of posterior wound retraction in this study [29]. Moreover, the above-mentioned three CCI features may cause changes to posterior corneal curvature, corneal astigmatism, and total corneal power; these

Anterior segment SD-OCT can highlight CCIs findings that are not as obvious by UBM, slit lamp. The ability to detect detailed postoperative corneal incision changes of standard or femtosecond laser-assisted cataract surgery is clinically important as it allows for the evaluation

**Figure 4.** High-resolution anterior segment SD-OCT clear corneal incision images of femtosecond laser-assisted cataract surgery showing a 1-plane CCI (panel A), 2-plane CCI (panel B), 3-plane CCI (panel C), stripping of Descemet's

membrane (panel D), posterior wound gape (panel E), and posterior wound retraction (panel F).

should be evaluated in future studies.

**3.1. Summary**

180 OCT - Applications in Ophthalmology

Capsular block syndrome (CBS), as an uncommon complication of phacoemulsification, is characterized by the accumulation of liquid between the IOL and posterior capsule [30]. Davison and Holtz first described this syndrome in 1990 and 1992, respectively [31, 32]. In

**Figure 5.** Slit lamp, Pentacam Scheimpflug, and AS-OCT images of an ultra-late capsular block syndrome before (panels A–D) and after surgery (panels E and F). Slit lamp photograph shows white proliferation tissue infero-nasally and nasal tight adhesion of anterior capsule opening fibrosis and IOL (panel A). Scheimpflug-based photography showing the contour of the IOL and the underlying milky-white fluid (panel B). Slit lamp photograph showing a large amount of white fluid trapped behind the IOL (panel C). AS-OCT showing a transparent IOL and accumulation of a milky-white liquefied substance between the posterior capsular bag and IOL (panel D). Slit lamp photograph showing posterior capsular folds and no milky-white liquid after surgery (panel E). AS-OCT shows that the capsular block syndrome is resolved after surgery, with parts of posterior capsule in contact with IOL and posterior capsule folds (panel F).

1993, Masket first used the term CBS to refer to this condition [33]. Due to a continuous capsulorhexis and adhesion of anterior capsule to the IOL, the exchange of aqueous between the anterior chamber and inner capsular bag gets blocked and fluid is retained behind the IOL [34]. Generally, CBS is related to IOL implantation in the capsular bag, but it has also be reported in cases with IOL implantation in the sulcus [35, 36]. Various manifestations of CBS, such as decreased visual acuity, ocular hypertension, closed angle glaucoma, and posterior capsule rupture have been reported. The two main reasons for vision loss include: (1) the effective position of IOL moves forward (myopic shift); (2) a white liquid accumulates behind the IOL (lacteocrumenasia) [30]. Based on time to development, CBS can be divided into three types: intraoperative capsular block, early postoperative CBS, and late postoperative CBS [37, 38]. Most intraoperative CBS occurs due to hydrodissection maneuvers in posterior polar or white cataract surgeries. Due to the block of capsulorhexis borders, liquid accumulates between the posterior nucleus and the posterior capsule. Increasing pressure in the capsular bag may cause posterior capsular rupture and even lens luxation into the vitreous [38]. Early postoperative CBS occurs 1–15 days after cataract surgery. The two main causes are as follows: (1) viscoelastic accumulation behind the IOL; (2) osmotic gradient behind the IOL induced by viscoelastic materials or trapped lens fragments [38, 39]. On average, late postoperative CBS occurs approximately 3.8 years after cataract surgery and deposition of a white fluid (proliferation and pseudo-metaplasia of the lens epithelium) is found between the IOL and posterior capsular bag [34, 40].

and treatment follow-up. Anterior segment SD-OCT offers extraordinary anatomic details, the more accurate diagnosis, and the potential of quantitative measurement to improve the

OCT Application Before and After Cataract Surgery http://dx.doi.org/10.5772/intechopen.77281 183

**Figure 6.** Slit lamp, UBM, and AS-OCT images of a late postoperative capsular block syndrome before Nd:YAG laser treatment. Slit lamp photograph showing capsulorhexis edge (red arrow), anterior IOL optic tightly in contact with the entire anterior capsule (panel A). Slit-lamp biomicroscopy showing transparent fluid behind the IOL (panel B). Due to the limited imaging penetration, UBM image showing artifacts (purple arrow) but not the posterior capsule (panel C). Due to limited imaging depth, spectral-domain AS-OCT fails to show posterior IOL surface (orange arrow), tight adhesion between anterior IOL surface and capsulorhexis edge (green arrow), and posterior capsule (panel E, blue arrow) in one cross-sectional image (panels D and E). Time-domain AS-OCT showing IOL thickness around 1.5 mm (yellow line segment) and the distance between IOL and posterior capsule of about 3.1 mm (white line segment) in one

**Figure 7.** Slit-lamp and AS-OCT images of a late postoperative capsular block syndrome after Nd:YAG laser treatment. Slit-lamp photograph shows irregular posterior capsule rupture (red arrow) after ND:YAG laser treatment (panel A). Spectral-domain AS-OCT cross-sectional image showing posterior capsule breaks with capsular edge rolling and significant decrease in the distance between the IOL and posterior capsule (compared to **Figure 6** panel F). The tight adhesion between anterior IOL surface and anterior capsulorhexis edge (yellow arrow) may prevent the IOL from falling

into the vitreous cavity through the big posterior capsule rupture (panel B).

assessment of treatment efficacy.

cross-sectional image (panel F).

A simple, clinical examination can diagnose most CBS cases. With the development of ophthalmic imaging technology t, a definitive diagnosis can be achieved using Scheimpflug-based photography, AS-OCT, or anterior segment UBM. Compared with Scheimpflug-based photography, spectral domain AS-OCT fails to provide complete anterior chamber information but it can provide more details about the IOL and any fluid between the IOL and posterior capsular bag (**Figure 5**).

In some CBS cases with relatively transparent fluid behind the IOL and a large distance between IOL and posterior capsule, UBM, Scheimpflug-based photography or AS-OCT can just demonstrate a partial cross-sectional image (**Figure 6**).

Compared to surgical management, we may also choose anterior or posterior capsulotomy with a Nd:YAG laser to treat CBS, especially for early postoperative and non-cellular late postoperative cases [41]. Due to the relatively lower success rate and higher recurrence rate for anterior capsulotomy, some doctors may choose posterior capsulotomy [42]. In some cases, posterior capsulotomy may cause unexpected irregular posterior capsule rupture, which may cause the IOL to drop into the vitreous cavity (**Figure 7**). Therefore, surgical management is a better choice for late CBS, especially incases with dense white liquid, which makes aiming the Nd:YAG laser accurately almost impossible, and the capsulotomy may cause IOP increase or vitreous inflammation [43]. As an important imaging technology, with the imaging depth enhanced, more and more details about CBS and other posterior capsular related disease can be investigated using OCT.

#### **4.1. Summary**

While varying in cause and course, these CBS cases all consistently demonstrated the ability of anterior segment SD-OCT to clearly diagnose and delineate with impressive detail the onset and treatment follow-up. Anterior segment SD-OCT offers extraordinary anatomic details, the more accurate diagnosis, and the potential of quantitative measurement to improve the assessment of treatment efficacy.

1993, Masket first used the term CBS to refer to this condition [33]. Due to a continuous capsulorhexis and adhesion of anterior capsule to the IOL, the exchange of aqueous between the anterior chamber and inner capsular bag gets blocked and fluid is retained behind the IOL [34]. Generally, CBS is related to IOL implantation in the capsular bag, but it has also be reported in cases with IOL implantation in the sulcus [35, 36]. Various manifestations of CBS, such as decreased visual acuity, ocular hypertension, closed angle glaucoma, and posterior capsule rupture have been reported. The two main reasons for vision loss include: (1) the effective position of IOL moves forward (myopic shift); (2) a white liquid accumulates behind the IOL (lacteocrumenasia) [30]. Based on time to development, CBS can be divided into three types: intraoperative capsular block, early postoperative CBS, and late postoperative CBS [37, 38]. Most intraoperative CBS occurs due to hydrodissection maneuvers in posterior polar or white cataract surgeries. Due to the block of capsulorhexis borders, liquid accumulates between the posterior nucleus and the posterior capsule. Increasing pressure in the capsular bag may cause posterior capsular rupture and even lens luxation into the vitreous [38]. Early postoperative CBS occurs 1–15 days after cataract surgery. The two main causes are as follows: (1) viscoelastic accumulation behind the IOL; (2) osmotic gradient behind the IOL induced by viscoelastic materials or trapped lens fragments [38, 39]. On average, late postoperative CBS occurs approximately 3.8 years after cataract surgery and deposition of a white fluid (proliferation and pseudo-metaplasia of the lens epithelium) is found between the IOL and posterior

A simple, clinical examination can diagnose most CBS cases. With the development of ophthalmic imaging technology t, a definitive diagnosis can be achieved using Scheimpflug-based photography, AS-OCT, or anterior segment UBM. Compared with Scheimpflug-based photography, spectral domain AS-OCT fails to provide complete anterior chamber information but it can provide more details about the IOL and any fluid between the IOL and posterior

In some CBS cases with relatively transparent fluid behind the IOL and a large distance between IOL and posterior capsule, UBM, Scheimpflug-based photography or AS-OCT can

Compared to surgical management, we may also choose anterior or posterior capsulotomy with a Nd:YAG laser to treat CBS, especially for early postoperative and non-cellular late postoperative cases [41]. Due to the relatively lower success rate and higher recurrence rate for anterior capsulotomy, some doctors may choose posterior capsulotomy [42]. In some cases, posterior capsulotomy may cause unexpected irregular posterior capsule rupture, which may cause the IOL to drop into the vitreous cavity (**Figure 7**). Therefore, surgical management is a better choice for late CBS, especially incases with dense white liquid, which makes aiming the Nd:YAG laser accurately almost impossible, and the capsulotomy may cause IOP increase or vitreous inflammation [43]. As an important imaging technology, with the imaging depth enhanced, more and more details about CBS and other posterior capsular related disease can

While varying in cause and course, these CBS cases all consistently demonstrated the ability of anterior segment SD-OCT to clearly diagnose and delineate with impressive detail the onset

just demonstrate a partial cross-sectional image (**Figure 6**).

capsular bag [34, 40].

182 OCT - Applications in Ophthalmology

capsular bag (**Figure 5**).

be investigated using OCT.

**4.1. Summary**

**Figure 6.** Slit lamp, UBM, and AS-OCT images of a late postoperative capsular block syndrome before Nd:YAG laser treatment. Slit lamp photograph showing capsulorhexis edge (red arrow), anterior IOL optic tightly in contact with the entire anterior capsule (panel A). Slit-lamp biomicroscopy showing transparent fluid behind the IOL (panel B). Due to the limited imaging penetration, UBM image showing artifacts (purple arrow) but not the posterior capsule (panel C). Due to limited imaging depth, spectral-domain AS-OCT fails to show posterior IOL surface (orange arrow), tight adhesion between anterior IOL surface and capsulorhexis edge (green arrow), and posterior capsule (panel E, blue arrow) in one cross-sectional image (panels D and E). Time-domain AS-OCT showing IOL thickness around 1.5 mm (yellow line segment) and the distance between IOL and posterior capsule of about 3.1 mm (white line segment) in one cross-sectional image (panel F).

**Figure 7.** Slit-lamp and AS-OCT images of a late postoperative capsular block syndrome after Nd:YAG laser treatment. Slit-lamp photograph shows irregular posterior capsule rupture (red arrow) after ND:YAG laser treatment (panel A). Spectral-domain AS-OCT cross-sectional image showing posterior capsule breaks with capsular edge rolling and significant decrease in the distance between the IOL and posterior capsule (compared to **Figure 6** panel F). The tight adhesion between anterior IOL surface and anterior capsulorhexis edge (yellow arrow) may prevent the IOL from falling into the vitreous cavity through the big posterior capsule rupture (panel B).
