Intraocular postoperative infections are a permanent concern for every eye surgeon. Although postoperative endophthalmitis is infrequent, with an incidence rate of 0.06% to 0.09% in the last decade,1–7 it represents a devastating complication in ophthalmic surgery.8 For this reason, the search for optimal procedures that will help reduce its incidence is a constant challenge.
Although the incidence of postoperative infections has a low rate, an increasing number of cases are now occurring after intravitreal injections of antivascular endothelial growth factor (VEGF) medications for choroidal neovascularization related to age-related macular degeneration,9–11 diabetic cystoid macular edema,12,13 and retinal vein occlusion.14 In fact, current protocols for the treatment of neovascular age-related macular degeneration dictate monthly or near-monthly injections of anti-VEGF.15 The risk of endophthalmitis reported after intravitreal injections is between 0.022% and 0.16%.16,17
The etiologic agents of acute postoperative endophthalmitis are generally microorganisms of the eyelid margin, conjunctiva, and tear film.18 The normal microbiota from the eyelid and conjunctiva has already been described.19 The most common bacteria isolated from the eyelids, conjunctiva, and tears are gram-positive bacteria, mostly coagulase-negative Staphylococcus spp. Depending on the study, the frequency of isolation of bacteria ranges from 16% to 100%, with microbial growth shown in approximately 50% of swabs from the conjunctiva and tears, and more than 50% of swabs from eyelids.19 The most commonly isolated microbes are Staphylococcus epidermidis, Corynebacterium spp, Staphylococcus aureus, Pseudomonas spp, or Proteus spp, which also have been isolated from intraocular infections. Bacteria present on the eyelid are responsible for acute postoperative endophthalmitis.18,20
To prevent the onset of postoperative endophthalmitis, several prophylactic strategies have been used. These approaches, which often feature use of topical antibiotics, are focused on reducing the bacterial load on the ocular surface assuming this could reduce the risk of endophthalmitis.8,21 The most commonly used treatments are perioperative topical antibiotics, preoperative topical antibiotics, intracameral antibiotics, antibiotics at the end of the surgery, and postoperative topical antibiotics.22 In addition to antibiotics, the antiseptic povidone–iodine (PVI) 5% to 10% is topically applied to the cornea, the conjunctival sac, and to the periorbital area. Several studies have demonstrated that PVI reduces the microbiota in the conjunctiva.7,8,21,23
This study tested the efficacy of lid hygiene using commercially available cleansing wipes to reduce the ocular surface microbiota in patients before ocular surgery.
This study adhered to the Helsinki Declaration and the Good Clinical Practice (GCP) guidance and was approved by the Research Ethics Committee of the Hospital Clínico San Carlos (Madrid, Spain). All patients gave written informed consent.
This single-center, prospective, single-blind phase IV study included adults of either sex, who were scheduled for ocular surgery after the treatment. Exclusion criteria included any kind of ocular or systemic disease, past or present, and any ocular and/or systemic treatments/antibiotics within the last 6 months.
The study lasted 5 days and the patients were examined at day 0 (D0), day 3 (D3), and day 5 (D5). The 5-day treatment was applied to only 1 eye that is, the eye selected for surgery; the other eye served as control with no treatment applied. Patients were instructed to apply heat over the eye for 4 min. A small towel was heated in a microwave on full power for 10 to 15 sec (which rises towel temperature to approximately 40°C) which was repeated every 2 min. It was applied to the closed eye area with sufficient pressure to ensure that the towel remained in contact with the eyelids. Then patients massage, applying a gently pressure, the upper lid “inward–downward” and the lower lid “inward–upward,” to mobilize the debris adhered to the eyelashes and meibum, and finally they use a sterile eyelid wipe and slide it across the eyelid from the inside to the outside, to clean the upper and lower lids. The Blephaclean (Laboratoires Théa, Clermont-Ferrant, France) sterile wipes contain a solution of hyaluronic acid, capryloyl glycine, iris florentine, and centella asiatica. Hyaluronic acid can influence cell proliferation, differentiation, and dermal tissue repair.24 Capryloyl glycine and iris florentine extracts are natural emollients show antibacterial activity and present a sebum-regulator effect and centella asiatica acts repairing dermal tissue, increasing collagen production, and activating blood circulation.25
They were used twice-a-day for 5 days in the selected eye. Visual acuity was measured at D0 and D5, and a slit-lamp examination was performed in each visit, to ensure there was no adverse reaction on the treated tissues.
Procedures and Assessments
Microbiota samples were taken from the surface of the lower lid and the inferior conjunctival sac fundus of both eyes at D0, D3, and D5 using sterile swabs moistened with saline solution without administering topical anesthesia. The nontreated eye was used as a control and microbiota samples were obtained in the same way. Sterile gloves were used when taking the samples.
Samples were cultured in specific media on blood and chocolate agar plates and incubated aerobically for 48 hr at 37°C. Sterile cotton swabs (Materlab SL, Madrid, Toledo, Spain) were used wet with 50 µL of saline solution. The volume of saline was controlled and applied by a pipette. Initially a sample from the eyelid was taken and spread onto 1 semipart of the dish and, by the same procedure, another cotton swab was taken from the conjunctival sac of the conjunctiva and seeded onto the other semipart of the dish. Dishes were divided in two semiparts; the left side corresponding to the eyelid culture and the right side to the conjunctiva. Grown colonies were photographed with a high-resolution digital camera, and the total area of microbial growth on the plates was analyzed by ImageJ software.
The percentage of the area occupied by the colonies was determined as follows: (1) The original image of the plate, shown on the left side of Figures 1 and 2, is a full RGB TIFF, which was converted to 8-bit grayscale. Figure 2 shows full images of the dishes. The upper plates belong to the right eye and the lower plates to the left eye. (2) A mask was created by marking out the region where the colonies may grow. The mask is a semicircle covering half the plate, corresponding to the region in which the colonies from the lid or the colonies from the conjunctiva were grown. (3) The selected region is transformed to 1-bit image by selecting an adequate threshold. The contrast between the colonies and the background (culture medium) was very good and a sharp contour of the colonies was achieved. The final image is shown in Figure 1 (right). Black pixels correspond to colonies, and white pixels correspond to the culture medium. (4) The ratio of the area occupied by the colonies and the total available growing region was obtained as the ratio of the number of pixels set to 0 and the number of pixels set to 1.
Once the photographs of the dishes were taken, microorganisms were identified by Gram staining, catalase, coagulase, DNase, and mannitol fermentation tests.
Data are presented as mean±SD. Differences in microbiota numbers between D0, D3, and D5 were assessed using the Student t test, assuming a significance level of 0.05.
The study included 45 consecutive patients (17 men, 28 women) with a mean age of 53.8±6.3 years (range 45–73 years). Visual acuity in the treated eye was in a range between 1.0 and 0.54 logMAR and remained stable during the treatment, and the slit-lamp examination showed no adverse reaction on the treated tissues.
Microorganisms Present in the Eyelid and Conjunctiva
At D0, microbial analysis demonstrated similar profiles for eyelid and conjunctiva. Identified microbiota is shown in Table 1. The eyelid showed the presence of S. epidermidis and Corynebacterium spp (94.7% and 32.98% of the plates, respectively) as the most frequent microorganisms. In a smaller percentage, S. aureus, Micrococcus spp, and Bacillus spp (6.38%, 8.51%, and 1.06%, respectively) were isolated. From the conjunctival swabs, S. epidermidis and Corynebacterium spp (54.26% and 38.29%) were identified as well as S. aureus and Micrococcus spp (5.32% and 1.06%).
The microbial area of growth on the plates was measured according to the method described in the methods section. A photograph of a typical petri dish, along with the mask used for measuring the area occupied by the colonies is shown in Figure 1. The colonies' area analysis yielded a higher microbial load from the eyelids (17.9%) compared with the conjunctiva (1.4%) in most of the samples, as it is seen in Figure 2. Percent reduction in microbial load on the eyelid in the treated eyes was 58% at D3 and 63% at D5 63% (P=0.001) (Fig. 3). The microbiota of the conjunctiva was lower than that of the eyelid. There was a reduction, although nonsignificant, of 72% and 69% at D3 and D5, respectively (Fig. 4) in the numbers of microbes on the conjunctiva. Table 2 and Figures 1 and 2 show the microbiota growing areas from eyelid and conjunctiva in all groups. There were no differences by sex.
In addition to the classical procedures such as cataract surgery, the number of intraocular interventions is increasing because of the development of new therapies. Endophthalmitis caused by microorganisms present on the ocular surface may occur as a consequence of these treatments. The results obtained in this study demonstrated a significant reduction in the microbiota present on the lids and conjunctiva after 3 days of rubbing the lids with the wipes, demonstrating the importance of lid hygiene before ocular surgery or an intraocular procedure, as a complementary prophylactic approach.
The percentages of microorganisms existing on the eyelids and conjunctiva in the study were similar to that described previously with the most commonly isolated bacteria being coagulase-negative staphylococci and, more specifically, S. epidermidis followed by Corynebacterium spp Between 20% and 80% of swabs from the conjunctiva and between 30% and 100% of swabs from the lids showed growth of the bacteria S. epidermidis.19 Carron et al.26 found the most common bacteria were coagulase-negative staphylococci (66.7%), followed by Corynebacterium spp (11.5%) from the conjunctiva, and Li et al.27 described a prevalence of 62.9% and 32.4% for S. epidermidis and Corynebacterium spp, respectively, from the conjunctiva. Vasavada et al.28 detected between 90.4% and 94.4% of Staphylococcus species from the conjunctiva, of which 71% were S. epidermidis. The rate of isolation of the same bacteria in the study by Höfling-Lima et al.29 ranged between 50% and 80% for the conjunctiva and between 76% and 100% for the eyelids.
The microbial isolation of the conjunctiva was reduced on presurgical prophylaxis of wiping the eye after briefly heating the eye. Hueso Abancens et al.30 presented a similar study analyzing the use of palpebral cleansing solution with capryloyl glycine over the conjunctiva microbiota. A clinical reduction was seen from the third day of applying the cleansing solution that lasted until day 5. In the study of Hueso Abancens et al.,30 the maximum reduction obtained after 5 days of treatment was approximately 10% and the main bacteria was Staphylococcus spp coagulase-negative. The smaller reduction found by Hueso Abancens et al.30 than this study could be due to the hygiene protocol used to clean the lids. In the study by Hueso Abancens et al.,30 the patients were not told to apply heat and massage the lids before using the cleansing solution.
In addition, many studies have been conducted on the reduction of eyelid and conjunctiva microbiota after the application of different antibiotics on their own or in combination with PVI. Höfling-Lima et al.29 examined the efficacy of topical lomefloxacin 0.3% and tobramicin 0.3% 3 days before cataract surgery in reducing biota, and showed statistical reductions in conjunctiva of 66.7% and in lid biota of 3.9% with lomefloxacin, and of 75% and 34.5%, respectively, with tobramicin.
Carron et al.26 described a 4.3% reduction in conjunctiva biota after the administration of ciprofloxacin 0.3% 1 day before cataract surgery that increased to 60.9% after the application of PVI. The use of PVI before cataract surgery has become a standard of care and a mandatory step in reducing ocular surface microbiota. Apt et al.31 showed a 91% reduction in the number of colonies of the conjunctiva after the application of PVI. Halachmi-Eyal et al.32 reported a 38% reduction after the application of PVI 3 min before surgery and a 34% reduction with the topical application of moxifloxacin 0.5% 2 hr before surgery and PVI 3 min before surgery.
The percentage reductions in the microbiota from this study are comparable in some ways to those obtained after the application of topical antibiotics. Eyelid hygiene did not sterilize the tissue, it just decreased the number of bacteria present in the external tissue of the eye without modifying the composition of saprophytic biota on both eyelids and conjunctiva. The reason for these reduced values is probably due to the hygiene protocol that patients followed of cleaning their eyelids after the application of heat and the massage.
Although microbiota is present in eyelids and conjunctiva, the percentage of area covered by colonies shows an important microbial load from the eyelids, which highlights the need to maintain preoperative and postoperative asepsis of both eyelid and conjunctiva.
Results obtained from bacteria cultures can indicate the type of antibiotic prophylaxis to use for minimizing ocular postoperative infections: broad-spectrum antibiotics or, preferably, antibiotics with specific activity against gram-positive bacteria.
Eyelid hygiene cannot replace general preoperative procedures focused on preventing contamination, such as the use of PVI solutions for eyelids and conjunctiva or antibiotics. Nevertheless, eyelid hygiene can be used as a complementary prophylactic approach to prevent endophthalmitis.
The use of cleansing eyelid wipes may help in the case of undiagnosed blepharitis before cataract surgery or other kinds of ocular surgery, as they could also reduce the risk of postoperative endophthalmitis.
Further studies are needed regarding the convenience of the medical regimen of use 3 and 5 days before surgery; the time the microbiota takes to recover itself after the use of the eyelid wipes; and what occurs if the patient uses the wipes more than 5 days. Another aspect worthy of study is the usefulness of applying the eyelid wipes as a postoperative prophylaxis or the medical regimen of use. This study demonstrated that the application of heat and a massage to the eyelids before the use of the eyelid wipe improves the reduction in the microbiota present in the ocular surface in 5 days, and eyelid hygiene can be use as a complementary prophylactic approach to prevent ocular infections.
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Keywords:© 2016 Contact Lens Association of Ophthalmologists, Inc.
Ocular surface microbiota; Eyelid wipe; Cataract surgery; Ocular surgery