Mature Cataract
White opacity of the entire cortex: The entire cortex from the nucleus to the capsule appears white.
Loss of red reflex: The fundus becomes difficult to visualize, reducing surgical visibility.
White Cataract
Key Points at a Glance
Section titled “Key Points at a Glance”1. What is white cataract?
Section titled “1. What is white cataract?”White cataract is a general term for a condition in which the lens opacity has advanced to the point of appearing white. It includes mature cataract, intumescent cataract, hypermature cataract, and Morgagnian cataract.
The natural course of cataracts progresses from incipient to immature, intumescent, mature corticonuclear, and finally hypermature Morgagnian.
Most patients seek treatment at the incipient or immature stage, so white cataracts are relatively rare. A study in India found that 8% of 3,634 cataract patients had white cataracts. The high prevalence in low-income areas reflects limited access to medical care.
Given the surgical difficulty, recognizing and classifying these cataracts preoperatively is directly linked to good outcomes.
Q
What is the difference between white cataract and brunescent cataract?
A
Both are forms of mature cataract, but brunescent cataract primarily involves nuclear color change (nuclear sclerosis) and may preserve near vision relatively well. In contrast, white cataract primarily involves cortical liquefaction and swelling, causing severe visual impairment. While surgical difficulty is common, increased intraocular pressure due to liquefied cortex is a problem unique to white cataract.
2. Main Symptoms and Clinical Findings
Section titled “2. Main Symptoms and Clinical Findings”Subjective Symptoms
Section titled “Subjective Symptoms”- Severe vision loss: In mature cataracts, only light perception may remain. Blurred vision, photophobia, and eye fatigue also occur.
- Monocular diplopia: Due to refractive changes in the nucleus.
- Rapid vision loss: Intumescent cataracts can cause rapid visual deterioration.
Clinical Findings
Section titled “Clinical Findings”Slit-lamp microscopy reveals diffuse white opacity of the entire lens. Findings vary by type.
Intumescent Cataract
Lens swelling: The lens is swollen due to epithelial damage and fluid influx.
Increased intralenticular pressure: The liquefied cortex fills the lens, and fluid spurts out during puncture.
Vacuole formation: Vacuoles and wedge-shaped cortical opacities are observed on slit-lamp examination.
Hypermature / Morgagnian
Capsular shrinkage and wrinkling: Cortical material leaks from the capsule, causing the capsule to shrink (hypermature).
Floating nucleus: When liquefaction progresses significantly, the nucleus floats freely within the capsule (Morgagnian).
3. Causes and Risk Factors
Section titled “3. Causes and Risk Factors”The main risk factors for white cataract are as follows:
- Aging: The greatest risk for all cataracts. About 45% of people in their 50s and 85% in their 70s have some opacity.
- Ultraviolet and radiation exposure: Long-wave radiation, ultraviolet light, infrared light, X-rays, beta rays, etc.
- Systemic diseases: Diabetes, atopic dermatitis, thalassemia
- Medications: Long-term steroid use, chemotherapy (e.g., mitomycin C)
- Smoking and heavy drinking
- History of intraocular surgery: after radial keratotomy (RK)
- History of other eye diseases: uveitis, etc.
Dysfunction of lens epithelial cells related to protein changes in the Na⁺-K⁺ ATPase pump alters osmotic pressure, causing the lens to swell (mechanism of intumescent cataract). Changes in Ca²⁺-ATPase isoform expression also play a major role in white cataract formation.
4. Diagnosis and Examination Methods
Section titled “4. Diagnosis and Examination Methods”Diagnosis is based on slit-lamp microscopy. The following tests are useful for classification.
Classification Systems
Section titled “Classification Systems”Three methods are used to classify white cataracts.
Classification 1 (Slit-lamp microscopy): Evaluated based on three factors: intralenticular pressure, cortical status, and nuclear color. If pressure is elevated, it is classified as “intumescent”; if the cortex is milky white, it is classified as “hypermature”.
Classification 2 (A-mode ultrasound): Divided into three types. Type 1: intumescent with cortical liquefaction and high acoustic reflectivity; Type 2: large nucleus with small amount of white cortex; Type 3: fibrotic anterior capsule with low echo spikes.
Classification 3 (Preoperative OCT): The latest system, with four types directly linked to surgical strategy.
| OCT type | Features | Intralenticular pressure |
|---|---|---|
| Type 1 | Lamellar cortex, minimal cleft | Normal |
| Type 2 | Anterior convexity, hyperreflective cortical bundles | Elevated |
| Type 3 | Bulging cortex + water cleft | Elevated |
| Type 4 | Complete liquefaction of anterior subcapsular cortex | — |
The ESCRS guidelines recommend preoperative evaluation of the degree of bulging using anterior segment OCT.
5. Standard Treatment
Section titled “5. Standard Treatment”There is no drug treatment for white cataract. Although pirenoxine eye drops (Catalin®, Kary Uni®) and glutathione eye drops (Tathione®) are used to prevent cataract progression, they have no effect on improving vision. The only definitive treatment is surgery.
Surgical Treatment
Section titled “Surgical Treatment”The standard procedure is phacoemulsification (PEA) and intraocular lens (IOL) implantation. However, white cataract surgery is technically challenging, and the ESCRS guidelines recommend that it be performed by an experienced surgeon.
Important Preoperative and Intraoperative Measures
Section titled “Important Preoperative and Intraoperative Measures”The greatest challenge in white cataract surgery is creating a continuous curvilinear capsulorhexis (CCC). The two main difficulties are the loss of red reflex and increased intraocular pressure.
Anterior capsule staining: Essential for ensuring visibility. Types of staining dyes used:
- Indocyanine green (ICG): Good staining, frequently used
- Trypan blue (TB): Good staining, but caution for corneal endothelial toxicity at high concentrations (≥2.5 mg/mL)
- Brilliant blue G (BBG): Lower retinal toxicity than indocyanine green. Can be used in combination with vitrectomy.
- Fluorescein (FS): Low human toxicity
The ESCRS guidelines recommend capsular staining (e.g., trypan blue) and decompression and aspiration of liquefied cortex (“milking”) to reduce the risk of capsular rupture. High-viscosity OVD (e.g., Healon V®) and intravenous mannitol can also be used to reduce the risk of capsular rupture.
Recommended techniques by OCT type:
- Type 1: Single-step continuous curvilinear capsulorhexis using forceps or a needle cystotome
- Type 2: Two-step continuous curvilinear capsulorhexis with forceps → bimanual I&A for internal pressure decompression
- Type 3: Fluid aspiration with a needle → continuous curvilinear capsulorhexis with forceps
- Type 4: Continuous curvilinear capsulorhexis with forceps while decompressing the anterior chamber
Femtosecond laser-assisted cataract surgery
Section titled “Femtosecond laser-assisted cataract surgery”Femtosecond laser-assisted cataract surgery improves the accuracy of anterior capsulotomy.
Yamazaki et al. (2021) reported a retrospective study of femtosecond laser-assisted cataract surgery in 37 eyes of 30 patients with atopic cataracts. In cases including 9 eyes with intumescent white cataract (IWC), the overall success rate of free-floating capsulotomy was 86% (32/37 eyes). In the intumescent white cataract group, incomplete capsulotomy due to anterior capsule tags occurred in 4 eyes, which was significantly higher than in the non-intumescent white cataract group (p<0.05). Meanwhile, radial anterior capsule tears, vitreous prolapse, and IOL decentration did not occur in any case1).
Femtosecond laser-assisted cataract surgery can be safely performed even in difficult cases such as atopic cataracts, but it should be noted that the success rate of free-floating capsulotomy decreases in intumescent white cataracts.
Q
Can white cataract surgery be performed at all hospitals?
A
White cataract surgery is classified as a difficult case requiring an experienced surgeon. Preparation of anterior capsule staining dye and high-viscosity OVD is necessary, and precise anterior capsulotomy devices such as Zepto® may be useful in some cases. For high-difficulty cases, referral to a specialized facility with the necessary equipment and expertise is recommended.
6. Pathophysiology and Detailed Mechanisms of Onset
Section titled “6. Pathophysiology and Detailed Mechanisms of Onset”Multiple molecular mechanisms are involved in the formation of white cataracts.
- Changes in lens metabolism: The membrane integrity of mature lens fiber cells is lost, leading to protein oxidation and precipitation. This is underpinned by the disappearance of lens protective metabolites and changes in protease activity.
- Ion pump dysfunction: Protein changes in the Na⁺-K⁺ ATPase pump alter osmotic pressure, causing water to flow into the lens and resulting in swelling.
- Calcium pump abnormality: Changes in the expression of Ca²⁺-ATPase isoforms play a major role in the formation of white cataracts. This may cause osmotic changes that do not typically occur in nuclear cataracts.
- Progression of liquefaction: If cortical liquefaction persists, it progresses to a Morgagnian cataract where the nucleus floats freely within the capsule.
Regarding the mechanism of atopic cataracts, correlations with oxidative damage and chronic inflammation, as well as the possibility that scratching the face provides mechanical stimulation to the lens, have been suggested. In anterior subcapsular fibrosis, elongated cells positive for alpha-smooth muscle actin have been identified histologically.
7. Latest Research and Future Prospects (Investigational Reports)
Section titled “7. Latest Research and Future Prospects (Investigational Reports)”Two-Stage Anterior Capsulotomy in Femtosecond Laser-Assisted Cataract Surgery
Section titled “Two-Stage Anterior Capsulotomy in Femtosecond Laser-Assisted Cataract Surgery”In femtosecond laser-assisted cataract surgery for intumescent white cataracts, leakage of white milky fluid can shift the anterior capsule position and lead to incomplete capsulotomy. Two-stage anterior capsulotomy methods specific to intumescent cataracts, such as the laser-assisted mini-capsulotomy technique by Schultz et al. (2014), have been proposed and are advancing toward clinical application.
Zepto® Precision Anterior Capsulotomy Device
Section titled “Zepto® Precision Anterior Capsulotomy Device”Zepto® is a precision anterior capsulotomy device using a nitinol ring, and reports indicate it is useful for difficult cases such as small pupils, white cataracts, and corneal opacities. However, since the learning curve differs from that of standard continuous curvilinear capsulorhexis, it is recommended to first gain proficiency with standard cases before applying it to difficult cases.
8. References
Section titled “8. References”- Yamazaki K, Yoneyama J, Hayashi T, et al. Efficacy of femtosecond laser-assisted cataract surgery for cataracts due to atopic dermatitis. Case Rep Ophthalmol. 2021;12:41-47.
- Osher RH. Pearls for the young cataract surgeon: the white cataract. J Cataract Refract Surg. 2023;49(1):3-4. PMID: 36573761.
- Chee SP, Chan NS, Yang Y, Ti SE. Femtosecond laser-assisted cataract surgery for the white cataract. Br J Ophthalmol. 2019;103(4):544-550. PMID: 29907631.