【摘要】 目的：观察接受斜视手术的连续性斜视患者的临床过程和治疗效果。方法：连续性斜视患者（<45岁）分为两组：其中第1组为内斜视患者；第2组为外斜视患者。我们使用棱镜屈光度（PD）来测量患者的偏斜角，对第一次手术后的患者在随访期间（6mo内）进行保守疗法。同时选择随访6mo后偏斜角仍超过15PD的斜视患者进行再次手术。本实验所有参与对象均进行了强制性检查。所有二次手术患者均在全身麻醉下进行，并于术后3,15d；3,6mo进行追踪随访。结果：在整个研究期间有28.8％的患者发展成为连续性斜视。所有斜视患者主视眼（固视眼）的二次手术均在一次手术后6～9mo内进行。经过二次手术干预后，在随访期间两组患者均获得了很好的治疗效果，同时并未出现过矫的趋势。结论：在二次手术过程中我们需谨慎肌肉矫正以避免日后过矫。
【关键词】 连续性斜视;主视眼;手术矫正;海德拉巴
INTRODUCTION
Strabismus can be defined as the ocular misalignment resulting in to deviation of visual axis from bifoveal fixation. It is one of the frequent health problems, sometimes associated with neurological disorders such as cerebral palsy and craniofacial developmental anomalies. Generally the global prevalence of strabismus ranges from 3% to 5 %[1,2]. In a world wide survey, among different races, the strabismus was detected in 2% to 4% of white population and 0.6 % in Asians[3]. Donnelly et al[4] reported the prevalence of strabismus as 3.98%. In a study from Australia in 2006 the squint was diagnosed in 48 patients (2.8% of total population)[5]. In one local study the squint was detected in 1.4% subjects among Afghan refugees in Pakistan[6]. In another study from Peshawar Pakistan in 2004 the over all prevalence of strabismus was 2%[7]. The consecutive strabismus usually develops during long term followup after primary surgical correction of squint. The incidence of consecutive squint after first strabismus surgery has been reported to be 6%20%[8,9]. The surgical treatment for consecutive strabismus is required when the patients present with deviations greater than 15PD, do not respond to conservative treatment, developing amblyopia and experience limitations in eye movements[10]. In the present study the postoperative changes in deviation were observed in the patients undergoing surgical correction for consecutive strabismus.
PATIENTS AND METHODS
Patients This was a retrospective clinical analysis conducted on the patients of both sexes with consecutive strabismus, who underwent monocular surgery for horizontal squint six to eleven months before at unitIII Liaquat University eye hospital, Hyderabad of Liaquat University of Medical and Health Sciences/Jamshoro, Pakistan, from June 2003 to December 2008. The subjects suffering consecutive strabismus with deviation of more than 15 prism diopter(PD) and completing the postoperative followup of six months were included.
Methods After primary surgical intervention, on nondominant eye, the scheduled postoperative followup was done in out patient department by two permanently posted senior ophthalmologists and four medical officers. The informed consent of patients and attendants was obtained and complete orthoptic examination was carried out including bestcorrected visual acuity using Snellens chart and Echart for illiterate children, slit lamp biomicroscopy, applanation tonometry, and indirect ophthalmoscopy after dilatation using 90D and 78D fundoscopes. Ocular movements including versions and ductions were checked in cooperative patients.The ocular deviation was measured by prism and cover test for near (33cm) and far (6m) distance using a fixation target in the subjects having good bilateral visual acuity. The deviation by modified krimsky test was measured in patients with poor vision or dense amblyopia and children less than five years for whom the measurement for distance was not possible. During the course of postoperative followup, all the subjects developed consecutive strabismus with deviation of 15PD and less were managed conservatively by occlusion therapy, orthoptic exercises and refraction. The patients presenting with deviations of more than 15PD after six months followup and not responding to conservative therapy were selected for secondary surgical procedure. After admission routine investigations including blood complete picture, bleeding and clotting time, detailed urine analysis, Xray chest etc were carried out. The patients and concerned personnel were informed about the surgical outcome of a second surgery. Prophylactic antibiotic ophthalmic drops e.g., Ofloxacin and Chloramphenicol were used three to four hours interval a day before surgery. All subjects were operated under general anesthesia after getting fitness from a visiting physician and anesthetist. The surgical procedure consisted of monocular recession or resection of horizontal rectimuscles on second dominant eye. The muscle was exposed by a limbal conjunctival incision with two radial relieving incisions. Muscle was then separated from its attachments by round edge curved conjunctival scissors and undermined with muscle hook. Two whip stitches were taken with 60 poly gelactin 910 absorbable sutures at the upper and lower edges of muscle near its insertion (in muscle recession), and away from insertion in muscle cone (in muscle resection).The muscle was cut near its insertion during recession and away from insertion during muscle resection and allowed to retract. Sutures were brought out of conjunctival incision and left loose with one edge at 12 oclock and other at 6 oclock position in opposite directions. The amount of recession was measured with a caliper from the muscle insertion posteriorly and the muscle was sutured directly on sclera by piercing sclera with both the upper and lower suture needles facing each other. The needles were passed gently through half thickness sclera under resistance without penetrating deep in to uveal tissue. The smooth passage of a needle through sclera without resistance is the sign of uveal penetration. As the sutures were tied the retracted muscle pulled and brought forward to become adherent with the site of attachment. In case of muscle resection the retracted muscle was sutured at its anatomical insertion. Conjunctiva was closed with interrupted absorbable sutures. The antibiotic mixed steroid eye ointment (neomycin with betamethasone) was applied and the eye bandaged for 24 hours. The recession of medial rectus muscle in case of consecutive esotropia and recession of lateral rectus muscle for consecutive exotropia less than 30PD was experienced on opposite dominant eye. The resection of horizontal recti was performed in case of deviations more than 30PD. On every postoperative out patient followup visit the subjects were assessed for bestcorrected visual acuity, angle of deviation along with patients photograph. All patients were requested to complete postoperative followup criteria of this study.
Table 1 General characteristics of patients with consecutive strabismus(n=17)（略）
Figure 1 A 27year male with right eye consecutive esodeviation（略）
Figure 2 A 2.5year child with left eye consecutive esodeviation（略）
Figure 3 A 27year male after second surgery for right eye esodeviation（略）
RESULTS
Out of fiftynine patients operated for monocular surgery for horizontal strabismus (first surgery), seventeen (28.8%) subjects presented with consecutive strabismus within the study period. Four patients refused for second surgery while remaining thirteen subjects (esodeviation=8 and exodeviation=5) were selected for secondary surgical intervention. Ten patients out of thirteen completed the postoperative followup of six months. Successful surgical outcome was considered as angle deviation of less than 15PD at sixth month postoperative followup. The general characteristics of patients with consecutive strabismus are shown in Table 1.
The patients data in group 1 including preoperative angles of consecutive deviation (Figure 1, 2), surgical procedures and postoperative result (Figure 3, 4) is shown in Table 2.The data of subjects in group 2 (Figure 5, 6) are summarized in Table 3.
Table 2 Pre and postoperative clinical characteristics of group 1 (Esodeviation) n=8 (61.5%)（略）
Table 3 Pre and postoperative clinical characteristics of group 2 (Exodeviation)n=5(38.5%)（略）
Figure 4 A 2.5year child after repeat surgery on left eye esodeviation（略）
Figure 5 A 14year girl with left eye consecutive exodeviation（略）
Figure 6 A 14year girl after repeat surgery on left eye exodeviation（略）
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