Kaan Gündüz

Ankara University, Engüri, Ankara, Turkey

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Publications (127)274.11 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Aims: The purpose of this study is to calculate the treatment plans and to compare the dose distributions and dose-volume histograms (DVH) for 6 external radiotherapy techniques for the treatment of retinoblastoma as well as intensity-modulated radiotherapy (IMRT) and fractionated stereotactic radiotherapy (Cyberknife). Methods: Treatment plans were developed using 6 techniques, including an en face electron technique (ET), an anterior and lateral wedge photon technique (LFT), a 3D conformal (6 fields) technique (CRT), an inverse plan IMRT, tomotherapy, and conventional focal stereotactic external beam radiotherapy with Cyberknife (SBRT). Dose volume analyses were carried out for each technique. Results: All techniques except electron provided similar target coverage. When comparing conformal plan with IMRT and SBRT, there was no significant difference in planning target volume dose distribution. The mean volume of ipsilateral bony orbit received more than 20 Gy, a suggested threshold for bone growth inhibition. The V20 Gy was 73% for the ET, 57% for the LFT, 87% for the CRT, 65% for the IMRT, 66% for the tomotherapy, and 2.7% for the SBRT. Conclusions: This work supports the potential use of IMRT and SBRT to spare normal tissues in these patients.
    09/2015; DOI:10.5301/tj.5000406
  • Rövşen Nesirov · Kaan Gündüz · Esra Erden
    Turk Oftalmoloji Gazetesi 05/2015; 45(3):105-110. DOI:10.4274/tjo.99266
  • Feyza Çalış · Kaan Gündüz · Işınsu Kuzu · Esra Erden
  • Kaan Gündüz · Rengin Aslıhan Kurt · Esra Erden
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    ABSTRACT: Ectopic orbital meningioma is a rare orbital tumor usually affecting the medial orbit. We present two cases that occurred in a 56-year-old woman and a 28-year-old man. The tumors in both patients were subtotally excised via orbitotomy surgery and were located in the superior quadrant in one of our patients and in the temporal quadrant in the other. Following histopathologic diagnosis, external beam radiotherapy (EBRT) was administered to one patient and intensity modulated radiotherapy to the other. We identified 12 other well-documented cases of ectopic orbital meningioma previously reported. Ectopic meningioma should be considered in the differential diagnosis of medial as well as lateral and superior orbital tumors. The tumor is usually well-circumscribed but can be ill-defined in imaging studies. There are intralesional calcifications and sclerosis of adjacent bone in some cases. Ectopic orbital meningioma can recur after incomplete excision. Based on the efficacy of EBRT in optic nerve sheath meningioma, we used this treatment to decrease the risk of recurrence in our 2 patients and found no tumor recurrence at follow-ups of 24 and 74 months, but one patient had severe vision loss from radiation retinopathy.
    Survey of Ophthalmology 03/2014; 59(6). DOI:10.1016/j.survophthal.2014.01.009 · 3.85 Impact Factor
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    ABSTRACT: To evaluate the presentation patterns and results of management of retinoblastoma at a tertiary care center in Ankara, Turkey, with special emphasis on globe conservation rate in unilateral and bilateral intraocular retinoblastoma. Patients were grouped according to the International Classification of Retinoblastoma. For intraocular retinoblastoma, group E and some group D eyes underwent primary enucleation. Secondary enucleation was performed after failure of chemoreduction, focal treatments, external beam radiotherapy (EBRT), and intra-arterial chemotherapy used in various combinations. For extraocular retinoblastoma cases, treatment consisted of enucleation/exenteration or orbital biopsy, high-dose chemotherapy, and EBRT to the orbit and metastatic sites. During the study period from October 1998 to May 2010, 165 of 192 (85.9%) patients had intraocular disease and 27 (14.1%) patients had extraocular disease. In total, primary or secondary enucleation was performed in 70 of 94 eyes with unilateral retinoblastoma (74.5%) and in 34 of 142 eyes with bilateral retinoblastoma (23.9%). The overall globe conservation rate was 69.6%. Only one patient in the intraocular retinoblastoma group died of metastatic retinoblastoma to the central nervous system. Twenty of 27 patients (74.1%) with extraocular retinoblastoma were found to have metastasis to the central nervous system, bone, bone marrow, and/or lymph nodes. At a mean follow-up of 28.0 months (median: 12 months; range: 1 to 120 months), survival was 33.3% despite intensive treatment. The overall risk of enucleation was 75% in eyes with unilateral retinoblastoma and 24% in eyes with bilateral retinoblastoma. Extraocular retinoblastoma carries a 75% risk of systemic metastasis and 67% risk of death. [J Pediatr Ophthalmol Strabismus 20XX;XX(X):XX-XX.].
    Journal of Pediatric Ophthalmology & Strabismus 08/2013; 50(5):1-8. DOI:10.3928/01913913-20130730-02 · 0.75 Impact Factor
  • Turk Oftalmoloji Gazetesi 01/2013; 43(5):335-339. DOI:10.4274/tjo.60252
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    ABSTRACT: Choroidal nevi are frequently seen, benign intraocular tumors originating from the uvea. The majority of choroidal nevi are asymptomatic and diagnosed incidentally. However, they can be symptomatic due to decompensation and metaplasia of the retinal pigment epithelium, photoreceptor atrophy, or choroidal neovascularization. They tend to have a low potential for malignant transformation. Serous macular detachment secondary to choroidal nevi is a cause of severe visual morbidity. The diagnosis and treatment may cause difficulties for physicians. In this report, we present three cases of serous macular detachment secondary to choroidal nevi and discuss its clinical features and treatment options.
    Retina-Vitreus 09/2012; 20(3):238-242.
  • Kaan Gündüz · Teksin Eryilmaz
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    ABSTRACT: This article reports the case of a 45-year-old man with systemic myasthenia gravis who developed right upper eyelid ptosis. One month after thymectomy surgery, he developed bilateral upper eyelid retraction. Lid retraction in the absence of thyroid eye disease is uncommon in myasthenia gravis, although it can develop during periods of medical treatment and after thymectomy surgery. Exclusion of thyroid disease is essential before ascribing lid retraction to myasthenia gravis.
    Annals of Ophthalmology 04/2012; 32(2):146-148. DOI:10.1007/s12009-000-0037-y · 0.17 Impact Factor
  • Melis Palamar · Onder Uretmen · Kaan Gündüz
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    ABSTRACT: Purpose: To report a case of choroidal osteoma that developed subretinal hemorrhage after photodynamic therapy (PDT). Methods: Interventional case report. Results: An 8-year-old boy was brought to our attention because of mild visual loss in his left eye. The visual acuity was 20/25. A subfoveal yellow-orange-colored lesion, measuring 5.0 mm × 4.5 mm in base diameter was detected in the left eye. B-mode ultrasonography showed an acoustically solid 2.0-mm-thick mass with orbital shadowing. Orbital computed tomography confirmed the presence of calcium, and choroidal osteoma was diagnosed. As there was a decrease in the best-corrected visual acuity (20/30) and the lesion showed growth (6.0 mm × 6.0 mm), PDT was performed at 6 months follow-up. The day after PDT, the visual acuity was counting fingers at 1 m and a subretinal hemorrhage over the lesion was detected. Two weeks after PDT, subfoveal hemorrhage dissappeared with some retinal pigment epithelial hyperplasia and visual acuity increased back to 20/30. Conclusion: Although PDT can induce decalcification in choroidal osteomas, it should not be performed in subfoveal osteomas unless there is evidence to treat the lesion such as the presence of choroidal neovascularization.
    Retin Cases Brief Rep 01/2012; DOI:10.1097/ICB.0b013e318223537c
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    ABSTRACT: We report three cases of corneal melanoma: two without conjunctival primary acquired melanosis or melanoma and one with a history of conjunctival melanoma. Report of 3 cases with corneal melanoma and literature review. Medical records of three patients with the diagnosis of corneal melanoma were reviewed. Total excisional biopsy with corneal epitheliectomy using 20% ethanol was performed. Postoperative topical chemotherapy with 0.04% mitomycin-C was used for 4 weeks as adjunctive therapy. The follow-up ranged from 13 months to 7 years. Each of the two patients experienced two recurrences. One was treated in a fashion similar to that of the initial tumor, and the other was treated by enucleation. None of the patients developed regional or distant metastasis. Malignant melanoma can rarely occur on the cornea with no contiguous conjunctival component. Eye-conserving treatment should be attempted first. Recurrences may occur, and a close follow-up is necessary.
    Eye & contact lens 12/2011; 38(5):341-4. DOI:10.1097/ICL.0b013e318237d195 · 1.47 Impact Factor
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    ABSTRACT: Purpose To evaluate the role of photodynamic therapy (PDT) for symptomatic high risk choroidal melanocytic (HRCM) lesions with subretinal fluid extending to the fovea.Methods Retrospective review of the medical records of all patients who underwent PDT for a HRCM lesion.Results Seventeen patients were included in the study. The mean initial visual acuity was 20/80 (range CF-20/20). The mean initial tumor thickness was 1.23 mm (range 0.66-1.93). All tumors presented at least 2 risk factors for growing. The mean number of PDT sessions was 1.41 (range 1-3). The mean final visual acuity improved to 20/60 (range CF- 20/20). Subretinal fluid was reduced in all (100%) eyes and had completely disappeared in 9 (53%) eyes after PDT. The mean final tumor thickness increased to 1.24 mm (range 0.66 to 2.01) at a mean follow-up of 22.47 months (range 6-60). Tumor thickness increased in 3 (18%) eyes, remained unchanged in 13 (76%) eyes, and 1 (6%) lesion shrank down to a flat chorioretinal scar.Conclusion PDT prevents vision loss with improvement of choroidal leakage in HRCM lesions with serous macular detachment, but doesn´t allow a good local tumor control. Longer follow-up is required to determine its value in these patients.
    Acta ophthalmologica 09/2011; 89(s248). DOI:10.1111/j.1755-3768.2011.4161.x · 2.84 Impact Factor
  • Kaan Gündüz · Rengin A Kurt · Esra Erden
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    ABSTRACT: A 40-year-old man presented with a progressively growing left orbital mass producing proptosis. Orbital MRI revealed a large bilobed mass that was isointense with respect to the extraocular muscles on T1-weighted images and demonstrated heterogenous contrast enhancement. T2-weighted images revealed a markedly heterogenous internal appearance with fluid-fluid levels. The mass was completely excised in one piece. Histopathologically, the encapsulated tumor consisted mostly of spindle-shaped tumor cells with elongated nuclei forming bundles without obvious mitosis. Richly cellular areas were consistent with the Antoni A pattern, and more hypocellular edematous areas were consistent with the Antoni B pattern. Hemorrhagic and cystic areas were seen within the tumor. The tumor cells stained diffusely positive with S-100 protein. Findings were consistent with the diagnosis of orbital schwannoma. Fluid-fluid levels are usually seen in some vascular and bone tumors and soft tissue lesions. Fluid-fluid levels have previously been reported to occur in intracranial but not in orbital schwannomas. This case demonstrates that orbital schwannoma can also display fluid-fluid levels on MRI, which were thought to be due to intralesional hemorrhage in this case.
    Ophthalmic plastic and reconstructive surgery 05/2011; 27(3):e51-4. DOI:10.1097/IOP.0b013e3181e2f96f · 0.88 Impact Factor
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    ABSTRACT: To evaluate the role of primary transpupillary thermotherapy (TTT) in the treatment of choroidal melanocytic lesions. Retrospective chart review of 24 patients (24 eyes) with choroidal melanocytic lesions, including 20 choroidal melanoma and four choroidal nevus treated with primary TTT. Choroidal nevus cases treated with primary TTT either demonstrated risk factors for growth into an early melanoma or had overlying choroidal neovascularization. The mean initial tumor basal diameter was 6.6 (3.0-10.0) mm and the mean initial tumor thickness was 3.0 (1.0-5.0) mm. The mean number of TTT sessions was 2.5 (1-6). The mean decrease in tumor thickness was 1.2 mm (from 3.0 to 1.8 mm) at a mean follow-up of 22.7 (range 3-90) months. On the LogMar scale, visual acuity was stable at 1.0. Complications occurred in 50% of eyes. The most frequent complications were vitreous hemorrhage [5 patients (20.8%)], focal cataract [5 patients (20.8%)], iris atrophy [4 patients (16.6%)] and posterior synechia [4 patients (16.6%)]. There was no significant difference in the complication rate with respect to tumor thickness >3 mm versus tumor thickness ≤3 mm and juxtapapillary versus nonjuxtapapillary location (Fisher's exact test, P>0.05). Kaplan-Meier curves showed that 9% of eyes develop recurrence by 1 year and 27% develop recurrence by 5 years after primary TTT. Two eyes (8.3%) were enucleated because of neovascular glaucoma and one eye (4.1%) was exenterated because of extraocular tumor recurrence. Globe salvage was achieved in 21 patients (87.5%). One patient (4.1%) with extraocular tumor recurrence developed liver metastasis and expired. Although TTT may be useful in the treatment of small choroidal melanocytic lesions, the high complication and recurrence rates warrant close monitoring of patients after primary TTT even when a flat chorioretinal scar has been achieved.
    Middle East African journal of ophthalmology 04/2011; 18(2):183-8. DOI:10.4103/0974-9233.80711
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    ABSTRACT: To evaluate the role of photodynamic therapy (PDT) for patients with symptomatic choroidal nevi involving the fovea or located near the fovea with subretinal fluid extending to the fovea. Retrospective review of five patients who underwent PDT for choroidal nevi at two separate centers in Ankara and Barcelona. The mean initial logMAR visual acuity was 0.5 (range: 0 to 1.5). The mean largest tumor base diameter was 3.2 mm (range: 2.1-4.5 mm) and the mean tumor thickness was 1.1 mm (range: 0.7-1.6 mm). The mean number of PDT sessions was 1.6 (range:1-3). The mean final tumor thickness was 1.0 mm (range: 0-1.6 mm) at a mean follow-up of 19 months (range: 12-32 months). The mean final logMAR visual acuity was 0.4 (range: 0-1.5). Subfoveal fluid disappeared or decreased significantly in 4 of 5 eyes (80%) after PDT. PDT led to resolution of subretinal fluid with preservation of visual acuity in many symptomatic choroidal nevi in this study. Careful case selection is important as PDT of indeterminate pigmented tumors may delay the diagnosis and treatment of an early choroidal melanoma and thereby increase the risk for metastasis.
    Middle East African journal of ophthalmology 03/2011; 18(4):309-13. DOI:10.4103/0974-9233.90134
  • Kaan Gündüz · Emine Catak · Esra Erden
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    ABSTRACT: To evaluate the role of optic nerve biopsy in the diagnosis and management of optic nerve and sheath tumors. Seven patients with progressive optic nerve and sheath tumors for whom treatment was deemed necessary were included in this study. Optic nerve biopsy via a medial transconjunctival orbitotomy approach was performed in all patients There were no complications related to the surgical procedure. Histopathological examination revealed that five patients had juvenile pilocytic astrocytoma (JPA) and two patients had optic nerve sheath meningioma (ONSM). All patients received external beam radiotherapy (EBRT). Many other benign and malignant optic nerve and sheath tumors have imaging features similar to those seen in JPA and ONSM. Therefore, it is important to establish histopathologic diagnosis before embarking on treatment. Furthermore, tissue diagnosis is required prior to EBRT in many institutions because of concerns about medicolegal liability. Optic nerve biopsy via a transconjunctival orbitotomy procedure in seven patients yielded histopathologic confirmation of the existing pathology and was not associated with any complications in this series.
    Orbit (Amsterdam, Netherlands) 08/2010; 29(4):190-3. DOI:10.3109/01676831003664368
  • Kaan Gündüz
    Middle East African journal of ophthalmology 07/2010; 17(3):189-90. DOI:10.4103/0974-9233.65485
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    ABSTRACT: To evaluate the results of ruthenium-106 (Ru-106) plaque radiotherapy alone (group A) or in combination with transpupillary thermotherapy (TTT) (group B) in the management of choroidal melanoma with tumor thickness (height) <8 mm. The tumors in each group were subclassified as those with thickness <or=5 mm versus those with thickness of >5 and <8 mm. In this retrospective review, the main outcome measures were globe conservation rate, the rate of a reduction of at least 50% in tumor thickness, treatment complications, visual acuity (VA) change, and metastasis. Kaplan-Meier curves for prediction of decrease in tumor thickness of at least 50% over time were constructed. A total of 54 patients (24 in group A and 30 in group B) were included in this study. The groups were matched with respect to patient age, tumor base diameter, tumor thickness, tumor distance to optic disc, tumor distance to foveola, and baseline visual acuity (VA). The mean follow-up was 24.6 months in group A and 44.9 months in group B. Globe conservation was achieved in 21 (87.5%) eyes in group A and in 26 (86.7%) eyes in group B. The globe conservation rates did not differ significantly between groups A and B or between tumors <or=5 mm in thickness and those >5 to <8 mm in thickness in each group (P > 0.05). There was no statistical difference between groups A and B in the rate of tumor thickness reduction of at least 50% (P> 0.05). There was a significant decrease in final VA compared to baseline VA in group B (P = 0.007) but not in group A. Radiation complications were similar in groups A and B. Liver metastasis occurred in two patients in group A and in one patient in group B. Statistical analysis could not be carried out for the latter two variables because of the small number of affected patients. Compared to Ru-106 plaque radiotherapy alone, Ru-106 plaque radiotherapy combined with TTT did not result in a significant change in the globe conservation rate or the rate of at least 50% reduction in tumor thickness in choroidal melanomas <8 mm in thickness. Although Ru-106 plaque radiotherapy is mainly used for choroidal melanomas >or=5 mm thick, it can also be considered in selected tumors with thickness between 5 and 8 mm with comparable tumor control.
    Japanese Journal of Ophthalmology 07/2010; 54(4):338-43. DOI:10.1007/s10384-010-0821-1 · 1.68 Impact Factor
  • Kaan Gündüz · Nikolaos E Bechrakis
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    ABSTRACT: Surgical resection of uveal melanomas is an alternative eye-salvaging approach to the more commonly used irradiation techniques. There are two surgical resection techniques: Transscleral resection or "Exoresection" via a partial lamellar sclerouvectomy and "Endoresection" via a pars plana vitrectomy. While exoresection is more applicable to anteriorly located tumors with ciliary body and/or iris involvement, endoresection is more suitable for posteriorly located tumor without ciliary body involvement. Both approaches are suitable for large tumors with >8 mm in thickness. In general, eyes containing these large tumors have a very dismal prognosis regarding long-term visual function, eye retention, and irradiation-induced side effects. By removing the tumor burden from the eye, histopathologic and cytogenetic information of the tumor is available and complications associated with the so-called toxic tumor syndrome are avoided. However, both types of surgical resection are challenging surgical procedures, bearing the risk of early and late postoperative complications.
    Middle East African journal of ophthalmology 07/2010; 17(3):210-6. DOI:10.4103/0974-9233.65494
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    ABSTRACT: Olopatadine topical ophthalmic solution is a potent antiallergic agent that has selective histamine H1-receptor antagonizing and mast cell-stabilizing activity. Olopatadine is available as a 0.1% formulation and, more recently, as a 0.2% formulation. The drug inhibits proinflammatory mast cell mediator release, specifically histamine, and the release of inflammatory lipid mediators such as leukotriene and thromboxane from human leukocytes and eosinophils. In preclinical and clinical studies, olopatadine has proven to be a safe, comfortable and effective medication for the treatment of seasonal and perennial allergic conjunctivitis. The drug effectively relieves itching, redness, chemosis, tearing and lid swelling related to ocular allergy, and is also helpful in the management of nasal allergic symptoms. This article will review the current literature on the safety and efficacy of olopatadine, and will discuss the role of olopatadine in treating ocular allergy.
    Expert Review of Ophthalmology 06/2010; 5(3):287-296. DOI:10.1586/eop.10.28
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    ABSTRACT: This paper describes a new technique to suture the radioactive plaque to sclera. The radioactive plaque is conventionally sutured to the sclera using 5/0 nylon sutures. The imbricated suture technique involves using a 1/0 silk or 2/0 mersilene suture imbricated with the 5/0 nylon suture when the nylon suture is tied and cut. The imbricated suture technique allows easy identification of the plaque at removal and provides a surface that separates the 5/0 nylon from the surface of the eyelet platform, making suture cutting easier and safer. The radiation exposure times ranged from 9.1 minutes to 14 minutes (mean: 10.8 minutes) during plaque insertion and from 2.8 to 3.3 minutes (mean: 3.0 minutes) during plaque removal with the imbricated suture technique. This technique may decrease radiation exposure time and may prevent inadvertent scleral damage.
    Clinical Ophthalmology 03/2010; 4:159-61. · 0.76 Impact Factor

Publication Stats

2k Citations
274.11 Total Impact Points


  • 1993–2014
    • Ankara University
      • • Department of Ophthalmology
      • • Faculty of Medicine
      Engüri, Ankara, Turkey
  • 2007–2009
    • Mayo Clinic - Rochester
      • Department of Ophthalmology
      Rochester, MN, United States
  • 1998–2001
    • Wills Eye Institute
      Philadelphia, Pennsylvania, United States
  • 1997–1999
    • Thomas Jefferson University
      • Wills Eye Institute
      Philadelphia, Pennsylvania, United States
  • 1996
    • Hacettepe University
      Engüri, Ankara, Turkey
  • 1995–1996
    • Konya Numune State Hospital
      Conia, Konya, Turkey