Hiroko Bissen-Miyajima, MD, PhD
Contents
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Ocular Surface Disorders |
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Diabetes |
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Retinitis Pigmentosa |
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Eyelid Abnormalities |
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Bleeding disorders |
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CHAPTER HIGHLIGHTS |
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The new technology of phacoemulsification and aspiration and intraocular lens (IOL) implantation facilitates cataract surgery with smaller incisions and fewer complications. These developments have expanded the indications for cataract surgery for eyes with other ocular pathologies.
Ocular surface disorders
Dry eye
Knowledge of the presence of pre-existing dry eye before ocular surgery became an important issue with the increasing worldwide popularity of laser in situ keratomileusis (LASIK). Research on the corneal effects of cataract surgery has focused primarily on the endothelium. However, the effects on the epithelium, such as superficial punctate keratopathy (SPK) and epithelial defects, seem to be more common. Patients often complain postoperatively of ocular discomfort with a dry-eye sensation. Dry eye after cataract surgery can be categorized into two groups: the first is the worsening of pre-existing dry-eye symptoms and the second is surgically induced dry eye. The possible effects of cataract surgery on the ocular surface are shown in Table 34-1.
Table 34-1 -- Effects of cataract surgery on the ocular surface
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Preoperative |
Dry eye |
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During surgery |
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Incision |
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Postoperative |
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Preoperative management
A Dry Eye Workshop recently determined that “dry eye is a multifactorial disorder of tears and the ocular surface associated with symptoms of discomfort or visual disturbances.”[1] If there is any doubt about the presence of dry eye before cataract surgery, the patient should be informed that the dry eye may worsen for a couple of months after cataract surgery. Epithelial defects after cataract surgery often develop in patients with decreased tear production. If dry eye is suspected, fluorescein staining of the corneal epithelium and rose bengal staining should be performed, and tear film break-up time should be determined before surgery. If SPK is present, artificial tears or eye drops containing hyaluronic acid should be prescribed to improve the corneal condition. If SPK is refractory to treatment, intracanalicular plugs should be considered. Eye drops containing a preservative such as benzalkonium chloride should be avoided.[2]
Surgical procedure
The side effects of topical anesthesia on the corneal epithelium are well known, and, therefore, application of anesthetic eye drops should be minimal. Exposure to the light source of the operating microscope also should be minimal. The type of incision (sclerocorneal or corneal) does not seem to be problematic in these patients.
Postoperative management
Eye drops containing a preservative tend to cause epithelial problems. Nonsteroidal anti-inflammatory drugs, such as diclofenac sodium, affect the corneal epithelium in certain cases. For patients already diagnosed with dry eye, only antibiotic and steroid regimens should be prescribed. Additional eye drops, such as artificial tears, increase the stability of the precorneal tear film. If SPK is severe in the early stage, the treatment plan may be adjusted to avoid resistant keratopathy. Severe SPK is sometimes seen 1 week after surgery (Figure 34-1). In such cases, all eye drops except artificial tears might have to be stopped. If no improvement is seen, autologous serum eye drops may be prescribed.[3] The procedure for making these eye drops is shown in Table 34-2. Another approach is to use an eye protector or goggles to avoid tear film evaporation.
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Figure 34-1 Superficial punctate keratopathy. Fluorescein staining over the entire cornea is observed. |
Table 34-2 -- Preparation of autologous serum application
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40mL of blood is obtained |
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↓ |
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Centrifuge for 5 min at 1500 revolutions/minute |
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↓ |
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Serum is separated |
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↓ |
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Serum put into a bottle with a coating protective against ultraviolet light |
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↓ |
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Serum diluted to 20% with physiologic saline |
Intracanalicular plugs are useful when the patient still has a dry-eye sensation. Absorbable plugs developed for dry eye after LASIK also can be used.
Stevens–johnson syndrome/ocular pemphigoid
Despite refinements to cataract surgery techniques, manipulation inside the eye in the presence of poor conditions on ocular surface remains challenging. The reconstruction of the ocular surface for severe cicatricial keratoconjunctivitis such as Stevens–Johnson syndrome or ocular pemphigoid has changed in the last 10 years. A two-step surgery, ocular surface reconstruction first and cataract surgery second, is advantageous over simultaneous surgeries consisting of cataract extraction and implantation of allograft limbal tissue and amniotic membrane.[4] With the development of tissue engineering, the application of cultivated autologous oral mucosal epithelial tissue seems to result in longer stability of the ocular surface.[5] Micro-incision surgery also is advantageous for these critical cases. The potential problems associated with cataract surgery in eyes with cicatricial keratoconjunctivitis are shown in Table 34-3.
Table 34-3 -- Complications in cataract surgery with cicatricial keratoconjunctivitis
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Eye lid |
Adhesion of palpebral and bulbar conjunctiva |
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Cornea |
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Wound closure |
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Ocular surface reconstruction
The patient's oral mucosal tissue is excised and the epithelial cells are cultured. Amniotic membrane is used for the substrate. A cultivated oral mucosal epithelial sheet is handled carefully and spread over the cornea after removing the cicatricial tissue (Figure 34-2). The sheet is sutured with 8-0 Vicryl and a medical-use contact lens is put in place.
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Figure 34-2 Cultivated oral mucosal epithelial transplantation. After removing the cicatricial tissue, the oral mucosal sheet is spread. |
Cataract surgery
If the corneal clarity improves after treatment with cultivated oral mucosal epithelium, cataract surgery can then be planned. The pupil should be dilated and the surgical technique with some additional aid considered. Regarding simultaneous surgery, either peribulbar or retrobulbar anesthesia is recommended. However, cataract surgery alone can be performed under routine anesthesia, i.e., under topical anesthesia.
The incision size is small, and both sclero-limbal and clear corneal incisions work well. Creating a capsulorrhexis in the presence of a hazy cornea is difficult. With the combination of capsule staining and an ophthalmic viscosurgical device (OVD), the capsulorrhexis is easier to make (Figure 34-3). Phacoemulsification using a small-diameter sleeve is beneficial for this type of complicated case. The pupil dilation is usually poor, and the small sleeve allows more space in which to manipulate the lens fragments (Figure 34-4). Another pearl for cases with severe corneal opacity is the use of a microkeratome. For these eyes, a penetrating corneal transplantation is critical. The microkeratome can be used to make the flap including the opaque corneal tissue, and then, under the flap, the clear corneal stroma can be confirmed.[6] In such cases, the surface of the corneal bed is rough and a contact lens or irrigating fluid should be applied over the surface to improve the visibility.
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Figure 34-3 Capsulorrhexis. The stained capsule can be observed. |
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Figure 34-4 Phacoemulsification. Implantation of amniotic membrane. A small sleeve allows more space to manipulate inside the eye. |
Even when the incision size is small, the reepithelization of the incision site may take longer than when performing uncomplicated cataract surgery. The thermal effects from the ultrasound tip can cause thermal burns on the tissue.[7] Since this complication is critical in these cases, recent technology with hyper-pulse phacoemulsification, which reduces the risk of thermal injury, is highly recommended. The corneal or scleral tissue is usually extremely thin. If the surgeon doubts that the incision will be self-sealing, the incision should be sutured (Figure 34-5).
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Figure 34-5 Suturing the incision. The corneal tissue is thin and suturing is mandatory. |
An OVD is a helpful tool during most procedures that protects the ocular tissue, such as the cornea, iris, and posterior capsule, with appropriate application. In addition, the OVD can be injected in order to separate the cortex and epinucleus from the capsule, and facilitates a safe and efficient phacoemulsification.
The new IOLs and insertion techniques also can be used during these complicated cases.
Postsurgical management is much easier than previous reconstruction with limbal allograft implantation using immunosuppression. In addition to the eye drops used routinely after cataract surgery, preservative-free artificial tears are administered frequently.
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Diabetes
In patients with diabetes, several complications seem to develop more often compared to normal patients (Table 34-4).
Table 34-4 -- Possible complications of cataract surgery in patients with diabetes
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Bleeding |
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Poor dilation |
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Delayed reepithelialization |
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Iritis |
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Possible effect on diabetic retinopathy |
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Insufficient wound closure |
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Infection |
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Increased blood sugar level due to topical or general steroid |
Preoperative management
Controlling diabetes is necessary. With the help of primary care doctor or internist, the HbA1c level should be adequately controlled.
Surgical procedure
Minimal invasiveness of the eye should be considered. Surgery sometimes becomes complicated due to poor pupil dilation. A new viscoadaptive OVD, such as Healon 5 (Advanced Medical Optics) is a helpful tool for dilating the pupil during any procedure. Excessive contact with the iris increases postoperative inflammation in the anterior chamber and may cause unexpected bleeding. If vitrectomy for diabetic retinopathy has been performed, the surgeon should be prepared for an unstable anterior chamber and pre-existing rupture of the posterior capsule. If laser coagulation for diabetic retinopathy is planned after cataract surgery, a larger anterior capsulotomy and the diameter of the IOL optic should be considered. There also may be difficulty in controlling intraocular pressure in patients undergoing hemodialysis. For those patients, the OVD in the anterior chamber should be removed completely at the end of surgery.
Postoperative management
Controlling anterior-chamber inflammation should be done more carefully than in uncomplicated cases. Some reports show a higher incidence of cystoid macular edema in patients with diabetes. Synechia is more common, and mydriatic eye drops can be used if posterior synechia may develop. Epithelial problems also are common. Surgeons may prescribe artificial tears for temporary use.
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Retinitis pigmentosa
Anterior subcapsular opacification is common in patients with retinitis pigmentosa. A very small opacity in the center of the lens may diminish the visual acuity, since the visual field is concentric in these patients. Some patients may complain of glare as the first symptom of cataract.
Surgical procedure
The capsule is thin and handling the capsule is complicated. The capsulorrhexis tends to decrease in size after surgery.[8] If the capsulorrhexis is extremely small, it should be enlarged at the end of surgery. Phacoemulsification is usually not difficult, since the cataract is an anterior subcapsular opacification and the nucleus is not very hard. An IOL with an ultraviolet cut is preferable for implantation.
Postoperative management
If the capsulotomy has become too small and affects the visual acuity, YAG laser capsulotomy is performed. Generally, sunglasses are recommended when patients are in sunlight.
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Eyelid abnormalities
Preoperative management
The surgical challenge for patients with eyelid abnormalities is obtaining sufficient ocular exposure. For most cases, a lid speculum cannot be used and a suture may be needed to open the upper and lower lids. Especially in cases of symblepharon, planning should include how to open the eyelid and perform cataract surgery with poor ocular exposure.
Surgical procedure
With any difficult case, the routine technique with which the surgeon is most confident should be performed. If the eye can be opened, the entrance of the incision should be well planned. In cases with symblepharon, pannus is also common, and the incision site should be planned to avoid unnecessary hemorrhaging. If phacoemulsification is completed, IOL implantation can be done in the usual manner. Another problem is intraoperative visibility. If the eye is opened with a suture or lid speculum, irrigating water will pool between the upper and lower lids, disturbing the visibility. A cannula that absorbs the water or a lid speculum with an aspiration system is helpful.
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Bleeding disorders
The use of anticoagulant therapy is most often seen for these disorders.[9] With the introduction of topical anesthesia and clear corneal incisions, routine cataract surgery can be performed in patients with bleeding disorders.
Preoperative management
If cataract surgery is performed through a clear corneal incision under topical anesthesia, the patient can remain on anticoagulant therapy.[7] If the use of peribulbar or retrobulbar anesthesia is planned during surgery, there is a risk of hemorrhage during the injection. The surgeon should consider the effects on systemic conditions associated with stopping the anticoagulants, such as thrombosis or embolism, and should consult the prescribing doctor if the systemic condition of the patient seems critical.
Surgical procedure
A technique should be chosen that poses less risk of encountering vessels. A clear corneal incision is ideal. Special caution should be taken when the eye is fixed with forceps, because this may cause excessive subconjunctival hemorrhaging.
Postoperative management
If a patient has discontinued the anticoagulant, the medication can be started again after the postoperative visit.
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References
[1]. Ocul Surf 2007; 5:75-92.No authors listed. The definition and classification of dry eye disease: report of the Definition and Classification Subcommittee of the International Dry Eye Workshop.
[2]. Gasset A.R.: Benzalkonium chloride toxicity to the human cornea. Am J Ophthalmol 1977; 84:169-171.
[3]. Tsubota K., Goto E., Shimmura S., Shimazaki J.: Treatment of persistent corneal epithelial defect by autologous serum application. Ophthalmology 1999; 106:1984-1989.
[4]. Bissen-Miyajima H., Monden Y., Shimazaki J., Tsubota K.: Cataract surgery combined with ocular surface reconstruction in patients with severe cicatricial keratoconjunctivitis. J Cataract Refract Surg 2002; 28:1379-1385.
[5]. Nishida K., Yamato M., Hayashida Y., et al: Corneal reconstruction with tissue-engineered cell sheets compose of autologous oral mucosal epithelium. N Engl J Med 2004; 351:1187-1196.
[6]. Shimmura S., Omoto M., Den S., Bissen-Miyajima H., Tsubota K., Shimazaki J.: Microkeratome-assisted phacoemulsification. J Cataract Refract Surg 2005; 31:1699-1701.
[7]. Bissen-Miyajima H., Shimmura S., Tsubota K.: Thermal effect on corneal incisions with different phacoemulsification ultrasonic tips. J Cataract Refract Surg 1999; 25:60-64.
[8]. Hayashi K., Hayashi H., Matsuo K., Nakao F., et al: Anterior capsule contraction and intraocular lens dislocation after implant surgery in eye with retinitis. Ophthalmology 1998; 105:1239-1243.
[9]. Shuler J.D., Paschal J.F., Holland G.N.: Antiplatelet therapy and cataract surgery. J Cataract Refract Surg 1992; 18:567-569.